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A <strong>TEST</strong> <strong>OF</strong> <strong>THE</strong> <strong>VALIDITY</strong> <strong>OF</strong> <strong>MORPHOMETRIC</strong> <strong>ANALYSIS</strong> <strong>IN</strong><br />

DETERM<strong>IN</strong><strong>IN</strong>G TECTONIC ACTIVITY FROM ASTER DERIVED DEMs<br />

<strong>IN</strong> <strong>THE</strong> JORDAN-DEAD SEA TRANSFORM ZONE


A <strong>TEST</strong> <strong>OF</strong> <strong>THE</strong> <strong>VALIDITY</strong> <strong>OF</strong> <strong>MORPHOMETRIC</strong> <strong>ANALYSIS</strong> <strong>IN</strong><br />

DETERM<strong>IN</strong><strong>IN</strong>G TECTONIC ACTIVITY FROM ASTER DERIVED DEMs<br />

<strong>IN</strong> <strong>THE</strong> JORDAN-DEAD SEA TRANSFORM ZONE<br />

A dissertation submitted in partial fulfillment<br />

of the requirements for the degree of<br />

Doctor of Philosophy<br />

By<br />

Husam Abbas Ata, B. A., M. A.<br />

Yarmouk University, 1995<br />

Yarmouk University, 1998<br />

May 2008<br />

University of Arkansas


ABSTRACT<br />

The Jordan-Dead Sea Transform (JDTZ) is an active tectonic zone which is<br />

located between the Dead Sea in the north and the Gulf of Aqaba in the south and extends<br />

approximately 245 km. The JDTZ has a complicated geomorphological setting and varied<br />

geology and it contains a number of active faults that were associated with several<br />

significant destructive earthquakes in the region. This research was initiated to develop a<br />

morphometric digital approach to examine the mountain front geomorphic form along the<br />

Jordan-Dead Sea Transform Zone to obtain intensive analysis of its potential as an<br />

indicator of seismic activity.<br />

Four ASTER scenes were used as a visual digital data reference to locate<br />

geomorphic forms along the mountain fronts in the study area. Using the ASTER<br />

generated DEMs of ±10m vertical accuracy as a base elevation reference layer, several<br />

significant mountain fronts and valley profiles were digitized using GIS technology to<br />

precisely determine their morphometric indices. The mountain front sinuosity (S mf ) and<br />

the ratio of valley floor width to valley height (V f ) morphometric indices were utilized to<br />

analyze the several mountain fronts and valleys in the JDTZ to determine their tectonic<br />

activity.<br />

The final morphometric analysis of S mf results indicated two major tectonic<br />

activity classes within the JDTZ. The active tectonic class 1 values range from 1.00 to<br />

1.30 while the moderate to less active class 2 values are >1.30. On the other hand, the V f<br />

analysis results suggest the existence of three tectonic activity classes. The active tectonic<br />

class 1 values range from ≤ 0.09 to 0.50, the moderate to less active class 2 values range<br />

from 0.51 to 1.88, and the less active (inactive) class 3 values are >1.88.


This dissertation is approved for<br />

Recommendation to the<br />

Graduate Council<br />

Dissertation Director:<br />

_________________________________________________________<br />

John C. Dixon, PhD<br />

Dissertation Committee:<br />

_________________________________________________________<br />

Jackson D. Cothren, PhD<br />

_________________________________________________________<br />

Pamela E. Jansma, PhD<br />

__________________________________________________________<br />

Thomas R. Paradise, PhD


DISSERTATION DUPLICATION RELEASE<br />

I hereby authorize the University of Arkansas Libraries to duplicate this dissertation<br />

when needed for research and/or scholarship.<br />

Agreed _____________________________________<br />

Refused ____________________________________


ACKNOWLEDGEMENTS<br />

“When I look back upon my early days, I am stirred by the thought of the number of<br />

people I have to thank for what they gave me or for what they were to me. . . . . I think we<br />

all live spiritually, by what others have given us in the significant hours of our lives” -<br />

Albert Schweitzer (1875-1965), a German philosopher, physician, musician, theologian,<br />

and the 1952 Nobel Peace Prize winner.<br />

From the formative stages of this dissertation, to the final draft, I owe an immense<br />

debt of gratitude to my supervisor, Dr. John C. Dixon, for his constant academic support<br />

and his words of encouragement and help throughout my graduate study and research. I<br />

would like to express thanks to Dr. Jackson Cothren, who never gave up on me. He was<br />

always interested in the work and helped me find answers regardless of the research<br />

challenges. I also want to thank Dr. Pamela Jansma and Dr. Thomas Paradise for their<br />

scholastic assistance and contribution to my research. Put these scholars together and it is<br />

the dynamic committee that words can never adequately describe. I would also like to<br />

extend my appreciation to the King Fahd Center for Middle East and Islamic Studies for<br />

the financial support they offered to conduct and maintain my graduate research.<br />

Second, I would like to acknowledge all the professors, technicians, and staff of<br />

the Center for Advanced Spatial Technologies (CAST) who were always willing to<br />

answer questions, and helped me locate valuable information. In addition, I would like to<br />

thank the environmental dynamics’ professors who taught and enlighten me. They were<br />

interested as I in seeing this study done. Moreover, I would like to thank the geosciences<br />

department’s staff and my fellow graduate students for their assistance and support.<br />

Finally, I would like to thank my faithful wife Nadia Khrais, without her support<br />

and steady encouragement this work would never have been completed. I also want to<br />

thank my parents, sisters, precious son, and family who offered me unconditional love,<br />

support, encouragement and surrounded me with their blessing and prayers.<br />

v


DEDICATION<br />

To my father and mother,<br />

To my two sisters, and<br />

To my wife and son,<br />

With love and gratitude<br />

vi


TABLE <strong>OF</strong> CONTENTS<br />

Title<br />

Page<br />

Abstract..………………………………………………………..………………… ii<br />

Acknowledgments...……………………………………………………………… v<br />

Dedication………..…………………….…………………………………………. vi<br />

Table of Contents………………………..…………………...…………………… vii<br />

List of Figures…..………..……………..………………………………………… x<br />

List of Tables…..…………………….…………………………………………… xvi<br />

List of Abbreviations – Keywords……………...………………………………… xvii<br />

1. Chapter One: Introduction…...………………………………………………… 1<br />

1.1. Research objectives…..……………………………………………………… 1<br />

1.2. Research problem…...……………………………………………………….. 1<br />

1.3. Justification of the Study..…………………………………………………… 4<br />

1.4. The Jordan-Dead Sea Transform Zone characteristics..…………………….. 6<br />

1.4.1. Geomorphology of the JDTZ.…………………….…………………….. 6<br />

1.4.1.1. Rifting Process and Extensional Tectonics..……………………… 16<br />

1.4.2. Structure and Geology of the JDTZ…..………………………………… 20<br />

1.4.2.1. Structure…..………………………………………………………. 20<br />

1.4.2.1.a. Wadi Araba…...…………………………………………… 20<br />

1.4.2.1.b. The Dead Sea…...………………………………………… 21<br />

1.4.2.2. Geology…...………………………………………………………. 23<br />

1.4.2.2.a. The Aqaba Complex...…………………………………….. 25<br />

1.4.2.2.b. The Araba Complex...…………………………………….. 25<br />

1.4.2.2.c. The Dead Sea..……………………………………………. 26<br />

1.4.3. Seismicity of the JDTZ..……………………………………………...… 30<br />

1.4.3.1. Regional tectonics of Jordan and its vicinity..………………….… 30<br />

1.4.3.2. Seismotectonic maps of Jordan..….………………………………. 33<br />

1.4.3.3. Seismic maps of the JDTZ..…….……………………………….... 37<br />

1.4.3.4. Jordan/JDTZ earthquakes data..……………………………...…… 42<br />

2. Chapter Two: Literature Review..…………………………………………...… 46<br />

vii


2.1. Introduction..………………………………………………………………… 46<br />

2.1.1. Morphometric analysis in geomorphology…......………………………. 46<br />

2.1.2. Remote sensing and GIS uses in geomorphology..……………………... 48<br />

2.2. Morphometric analysis approach..……………………………………...…… 50<br />

2.3. Geomorphic indices of active tectonics..………………………………….… 51<br />

2.3.1. The Hypsometric Curve and Hypsometric Integral (H i )..….…………… 52<br />

2.3.2. Drainage Basin Asymmetry (AF)..…………………………………...… 54<br />

2.3.3. Stream Length-Gradient Index (SL)..…………………………...……… 57<br />

2.3.4. Triangular Facets Index (Pf)..…………………………………...……… 59<br />

2.3.5. Mountain front sinuosity (S mf )..………………………………………… 62<br />

2.3.5.1. Choosing mountain fronts……………………..….….…………… 64<br />

2.3.6. Valley floor width to valley height ratio (V f )...……..……………...…… 65<br />

2.3.6.1. Choosing valley profiles..………………………………………… 66<br />

2.4. Satellite imagery and digital elevation models.…..…………..……………… 67<br />

2.4.1. Digital Elevation Model………...………………………………….…… 68<br />

2.5. Advanced Spaceborne Thermal Emission and Reflection Radiometer<br />

Satellite..……………………………………………………………………... 72<br />

2.5.1. ASTER data types..……………………………………………………... 73<br />

2.6. Previous studies in morphometric analysis….………………...…………..… 74<br />

2.7. Summary..…………………………………………………………………… 82<br />

3. Chapter Three: Materials and Methods..…………………..…………………... 84<br />

3.1. Introduction..………………………………………………………………… 84<br />

3.2. The digital morphometric approach..……………………...………………… 84<br />

3.2.1. Choosing mountain fronts..………………………………………...…… 85<br />

3.2.2. Choosing valley profiles..………………………………….…………… 85<br />

3.3. ASTER Stereo capability..……………………………………...…………… 85<br />

3.4. Obtaining ASTER imagery data..……………….…………………………… 87<br />

3.5. Viewing ASTER data in PCI Geomatica..……………………………...…… 89<br />

3.6. Generating ASTER DEMs…..………………………………….…………… 91<br />

3.6.1. Generating and extracting DEMs from ASTER data…..………..……… 92<br />

3.6.1.1. PCI Geomatica software……..…………………………………… 92<br />

viii


3.6.1.2. DEMs extraction process…..………………………………...…… 97<br />

3.6.1.3. The math model….……………………………………..………… 100<br />

3.6.1.4. DEMs editing process…..………………………………………… 118<br />

3.6.1.5. Transferring ASTER DEM to GIS environment…..……...……… 127<br />

3.7. Obtaining Landsat 7 ETM+ imagery…..………...……………………..…… 130<br />

3.7.1. Creating ASTER and Landsat composite images…..…………………... 130<br />

3.8. Obtaining vector data……..…………………………………………….…… 133<br />

3.8.1. Converting Interchange files to Shapefiles in ArcToolbox…...………… 134<br />

3.8.2. Digitizing vector data…...………………………………………….…… 137<br />

3.8.3. Digitizing mountain fronts and measuring sinuosity…..……..………… 138<br />

3.8.4. Digitizing valley profiles and measuring elevations and valleys’ widths. 153<br />

4. Chapter Four: Results and Discussion…..……………..……………………… 162<br />

4.1. Introduction…..……………………………………………...……….……… 162<br />

4.2. The tectonic morphometric analysis…...…………………..………………… 163<br />

4.2.1. Mountain front sinuosity results……...……………….………………… 166<br />

4.2.2. The ratio of valley floor width to valley height results…..……...……… 166<br />

4.3. Seismic activity at mountain fronts…..……………………………………… 168<br />

4.4. The accuracy of ASTER DEM data.….………………...…………………… 172<br />

4.5. ASTER DEM error test…..…………………………………………..……… 175<br />

4.6. Final results and tectonic activity classes…..………...……………………… 190<br />

5. Chapter Five: Conclusion…..……………………………...……...…………… 194<br />

5.1. Conclusion…...………………………………………………………………. 194<br />

5.2. Limitation of the Study…..…….……………………………..……………… 196<br />

5.3. Future directions/remarks…..…………………………...…………………… 196<br />

Bibleography……………………………………………………………………… 198<br />

Appendix A…..…………………………………………………………....……… 216<br />

ix


LIST <strong>OF</strong> FIGURES<br />

Figure<br />

Page<br />

1.1: Earthquakes in the Jordan-Dead Sea Transform and adjacent areas, 1900-<br />

1980……………………………………………………………………….…... 2<br />

1.2: Jordan-Dead Sea Transform Zone (JDTZ) dimensions.….….……………... 7<br />

1.3: East African Rift System …………………...………………...….................. 8<br />

1.4: Tectonic setting of the Middle East......…………………...…………...…… 9<br />

1.5: Wadi Araba Valley location map along the Jordan-Dead Sea Transform<br />

fault system………...………………...…………………...…………………... 10<br />

1.6: Block diagram along the central part of the JDTZ illustrating the tectonic<br />

style and the continuous rise of the graben floor.…………………...………... 12<br />

1.7: The Aqaba-Dead Sea-Jordan subgraben system….………………................ 13<br />

1.8: A block diagram showing the strike-slip geometry along the JDTZ<br />

representing the en echelon fault system.………………..………...…………. 15<br />

1.9: The seven pillars of Wisdom of southern Jordan………..………………….. 16<br />

1.10: The East Africa Rift Valleys as an example of the rifting process......……. 16<br />

1.11: Rift structure.…...………….…………………...………………..…............ 17<br />

1.12 Normal fault system..……………………………………………….……… 18<br />

1.13 (a) Symmetric horst and graben system (b) Half-graben system above the<br />

subhorizontal fault detachment.…………………...…….…………….…...…. 19<br />

1.14 Alluvial fans (bajadas) at the southern end along the eastern side of Wadi<br />

Araba…………………...…………………...………………………................ 20<br />

1.15 Dead Sea location map showing the two basins.………………..……......... 23<br />

1.16 Jordan-Dead Sea Fault simplified geological cross-section.……..……..….. 24<br />

1.17: A simplified geological cross section across the southern section of the<br />

Jordan-Dead Sea Transform.…………………...…………………................... 25<br />

1.18: Rock types and the locations of all mountain fronts in the JDTZ.…...……. 29<br />

1.19: Bouguer gravity anomaly map of Dead Sea transform, Jordan and Israel… 34<br />

1.20: (A) The thirteen seismic zones and (B) major faults within the thirteen<br />

seismic zones in Jordan and its vicinity………………..……………...…….... 35<br />

x


1.21: The Dead Sea fault and the adjacent branching faults…..………………… 37<br />

1.22: Seismic map of the Middle East 1900 – 1983…..………………………..... 38<br />

1.23: Seismic zones and active faults of Jordan and surrounding countries.......... 41<br />

1.24: Major earthquake events on Jordan, 19A.D. – August 1983….…………... 44<br />

1.25: Major earthquake events on Jordan, September 1983 – 2005…………….. 45<br />

2.1: Hypsometric curve derivation from drainage basin……….………………... 54<br />

2.2: Block diagram shows the effect of an asymmetry factor with a left side tilt<br />

on tributaries lengths…..…………………...…….……………........................ 55<br />

2.3: An example of calculating a drainage-basin transverse topographic<br />

asymmetry vector for a single stream segment.…………………………..…... 56<br />

2.4: Map showing the Stream Length-Gradient Index (SL)…………..…….….... 57<br />

2.5: Diagram shows the process of calculating the Stream Length-Gradient<br />

Index (SL).…………………...…………………...…………………............... 59<br />

2.6: Rapid and slow block uplift produces………..………...………………….... 60<br />

2.7: Circular and elongated basins.…………………...…..……………………... 61<br />

2.8: Location of older and younger triangular facets to mountain fronts……..…. 62<br />

2.9: Calculating mountain front sinuosity (S mf ) index…………………………... 63<br />

2.10: Mountain front sinuosity (S mf ) index...……………...…………...………... 63<br />

2.11: Calculating valley floor width to height ratio (V f )..………………..….…... 66<br />

2.12: Valley floor width to height ratio (V f ).…………………...………..……… 66<br />

2.13: The Aqaba 1:50,000-scale topographic map with 20m intervals..….…….. 70<br />

2.14: Flat map shows ASTER DEM global coverage of January 31,<br />

2004…………………………………………………………………..……….. 73<br />

2.15: Data structure of ASTER Level-1B granule…………….…………............ 75<br />

3.1: Simplified diagram of imaging geometry and data acquisition timing for<br />

ASTER along-track stereo image.…………………...………………….......... 86<br />

3.2: Simplified diagram of the imaging geometry for ASTER along-track stereo<br />

image “stereo configuration”...……………...……….………………….......... 87<br />

3.3: The USGS global visualization viewer showing ASTER scenes of Jordan... 88<br />

3.4: Focus is the first icon on the Geomatica Toolbar.………………..….……... 90<br />

3.5: Selecting ASTER VNIR sensor images.……………………...…...………... 90<br />

xi


3.6: Import File window.…………………………………..…………...………... 90<br />

3.7: ASTER 3-2-1 composite image of Aqaba.…………………………..……... 91<br />

3.8: Comparing raw images to epipolar images.…….…………..…………..…... 93<br />

3.9: Measuring height from ASTER stereopair parallax difference..……..…….. 95<br />

3.10: Summary of a standard ASTER DEM product generation process.…...….. 97<br />

3.11: OrthoEngine on the Geomatica Toolbar…………....…………….…..….... 99<br />

3.12: Opening new project from the processing step drop-down menu …...……. 100<br />

3.13: Reading satellite data from hard drive…...…………………………….….. 100<br />

3.14: Project Information window...…………………...………………………... 101<br />

3. 15: Setting project projection to UTM………………………………………... 101<br />

3.16: Setting the UTM zones……….…………………..........…………………... 102<br />

3.17: Setting the UTM rows……………………...…………….………………... 102<br />

3.18: Setting Earth Model (Ellipsoid)...………………...…...…………………... 102<br />

3.19: Setting GCPs to match the output file projection………………………….. 102<br />

3.20: Reading row ASTER data HDF files from the hard drive……………...…. 103<br />

3.21: Importing GCPs from file…………………………………...…………..… 104<br />

3.22: loading the 121 already available GCPs from image 3N file…………….... 104<br />

3.23: Dead Sea band 3N GCPs……………………...……………………….…... 105<br />

3.24: Dead Sea band 3B GCPs……………………...…………………….……... 105<br />

3.25: The image layout of bands 3N and 3B showing the location of all 121<br />

GCPs in the Dead Sea ASTER image..…………………...…………………... 105<br />

3.26: Start the Collect Ground Control Points and Tie Points manually function. 106<br />

3.27: An image show how two images connect through a tie point.…...…...…… 106<br />

3.28: Collecting tie points manually from both images…......…………………... 107<br />

3.29: Opening both uncorrected 3N and 3B images to manually collect tie<br />

points.…………………...………………………………...…………………... 108<br />

3.30: Collecting tie point window for Aqaba image 3N.……………..…......…... 108<br />

3.31: Automatically Collect tie points.……………..…….....………….………... 109<br />

3.32: Automatically Collect tie points uniformly over an entire image….…..….. 110<br />

3.33: Band 3N tie points (North Araba).……………………..………………….. 111<br />

3.34: Band 3B tie points (North Araba).……………...……...………………….. 111<br />

xii


3.35: Displaying overall image layout from both images.…...…...……………... 111<br />

3.36: Image layout of both bands 3N and 3B for the North Araba scene.…...….. 112<br />

3.37: Running Model Calculation to perform bundle adjustment.…..………….. 112<br />

3.38: Creating a DEM from stereo pairs using image correlation.………..…….. 113<br />

3.39: Create Epipolar image icon.…………………...……………….…...……... 114<br />

3.40: Generate Epipolar images window.…………………...…………..………. 114<br />

3.41: Extract DEM Automatically icon.…………………...…………..………... 115<br />

3.42: Automatic DEM extraction window showing all used options for Aqaba... 116<br />

3.43: The multi-resolution image pyramids.…………………….......…...……… 118<br />

3.44: The Dead Sea generated DEM.…………………...…………...…………... 119<br />

3.45: North Araba generated DEM.…………………...……….....……………... 119<br />

3.46: South Araba generated DEM.…………………...….…..……..…………... 120<br />

3.47: Aqaba generated DEM.…………………...………………...…..………… 120<br />

3.48: General view of the clipped GTOPO30 DEM of the Middle East showing<br />

the JDTZ.…………………...…………………...……………………..……... 122<br />

3.49: The XPace Tool……..…………………………………………………….. 124<br />

3.50: The Dead Sea final DEM.…………………...………………...…………... 127<br />

3.51: North Araba final DEM.…………………...……………….....…………... 127<br />

3.52: South Araba final DEM.…………………...………………..……...……... 127<br />

3.53: Aqaba final DEM.…………………...…………………...…...…………… 127<br />

3.54: Portion of the North Araba converted GRID file format to ASCII format... 129<br />

3.55: The converted North Araba DEM using ArcGIS ASCII to Raster<br />

command line.…………………...………..……………...………………….... 129<br />

3.56: Import from Interchange file window in ArcToolbox ………..…………... 134<br />

3.57: The Coverage to Shapefile tool in ArcToolbox…………………..……….. 135<br />

3.58: The Coverage to Shapefile tool window in ArcToolbox...………...……… 135<br />

3.59: The Define Projection Wizard in ArcToolbox………………………...…... 136<br />

3.60: The Define Projection Wizard window under Projections in ArcToolbox... 137<br />

3.61: Map shows the Dead Sea shoreline and Jordan borders before and after<br />

editing.…………………………………….…….…………………………….. 138<br />

3.62: The Gulf of Aqaba generated DEM and shaded relief….……………….… 139<br />

xiii


3.63: Dead Sea ASTER color composite 3-2-1………………………………….. 140<br />

3.64: Dead Sea ASTER-derived DEM…………………………………………... 141<br />

3.65: Dead Sea shaded relief…………………………………………………….. 142<br />

3.66: North Araba ASTER color composite 3-2-1………………………………. 143<br />

3.67: North Araba ASTER-derived DEM……………………………………….. 144<br />

3.68: North Araba shaded relief…………………………………………………. 145<br />

3.69: South Araba ASTER color composite 3-2-1………………………………. 146<br />

3.70: South Araba ASTER-derived DEM……………………………………….. 147<br />

3.71: North Araba shaded relief…………………………………………………. 148<br />

3.72: Aqaba ASTER color composite 3-2-1…………………………………….. 149<br />

3.73: Aqaba ASTER-derived DEM……………………………………………... 150<br />

3.74: Aqaba shaded relief………………………………………….…………….. 151<br />

3.75: An overall map of the mountain fronts and valley profiles…………….…. 152<br />

3.76: Calculating the V f value for valley profile #11 in the Dead Sea area……... 155<br />

3.77: The difference between the 2D image and the actual 3D topography of a<br />

given surface………………...…………..…...………….……………………. 156<br />

3.78: Collecting elevations from DEM as shapefile passes through raster<br />

horizontally, diagonally, and vertically.…………………….………………… 157<br />

3.79: Converting Aqaba 3D feature to points using XTools Pro...…………..….. 158<br />

3.80: General view from the Dead Sea area……………………………………... 160<br />

3.81: Collecting elevation data from profile #11 in the Dead Sea area...……..… 161<br />

4.1: Valley profile display of a V-shaped valley in South Araba and a U-shaped<br />

valley in the Dead Sea area……….…………………….……………….……. 162<br />

4.2: The tectonic activity classes of the S mf and V f indices results…………….... 165<br />

4.3: Network of earthquakes-mountain fronts’ relationship on the JDTZ<br />

showing earthquake events of M L 4 to 6 and tectonic zones, 19A.D. to<br />

August 1983…………………………………………………………………... 170<br />

4.4: Network of earthquakes-mountain fronts’ relationship on the JDTZ<br />

showing earthquake events of M L 4 to 6 and tectonic zones, September 1983<br />

to 2005……………………………………………………………………...…. 171<br />

xiv


4.5: The relationship between the ground coordinate system and the image<br />

coordinate system.………….……………...……….………………….……… 173<br />

4.6: The tectonic activity classes of all S mf and V f based on V f +σ Vf results….….. 189<br />

4.7: The active tectonic classes of the northern and southern regions of the<br />

JDTZ showing all S mf and V f +σ Vf results..………….………...……....……… 193<br />

xv


LIST <strong>OF</strong> TABLES<br />

Table<br />

Page<br />

1.1: Concise description of the mountain fronts rock types within the JDTZ...… 28<br />

2.1: The S mf and V f indices ranges of selected literature...……………………… 83<br />

3.1: ASTER scenes selected to cover the JDTZ study area...…………………… 89<br />

3.2: Specification for standard ASTER DEM products…………….…………… 96<br />

3.3: Number and type of tie points in each DEM coverage area...……………… 110<br />

3.4: Options used for all DEMs extraction processes within the study area…….. 115<br />

3.5: Overall number of digitized fronts in the JDTZ………...……………...…… 140<br />

3.6: Digitized valley profiles number and their distances upstream from<br />

mountain fronts in the JDTZ………………………………..………………… 154<br />

4.1: Brief results of all mountain fronts sinuosity (S mf ) and valleys floor width<br />

to valleys height ratio (V f ) analyses.………………………………..………… 164<br />

4.2: The percentage of the U- to V-shaped valley profiles in the JDTZ……….... 167<br />

4.3: MATLAB command lines……………………………………………...…… 183<br />

4.4: Dead Sea final σ Vf results and V f tectonic classes.....…………..…………… 184<br />

4.5: North Araba final σ Vf results and V f tectonic classes…..……..…………..… 185<br />

4.6: South Araba final σ Vf results and V f tectonic classes………….…….……… 186<br />

4.7: Aqaba final σ Vf results and V f tectonic classes...………………....………… 187<br />

4.8: Percentages change of all valleys tectonic classes after applying the ± σ Vf<br />

values.………………………………………………………………………… 191<br />

4.9: Final S mf and V f tectonic activity classes…………………………………… 192<br />

A.1: The Dead Sea S mf and V f results..…………………………..……………… 216<br />

A.2: The North Araba S mf and V f results..…………………….………………… 217<br />

A.3: The combined Dead Sea and North Araba S mf and V f results....…………… 218<br />

A.4: The South Araba S mf ) and V f results……………………………..………… 219<br />

A.5: The Aqaba S mf and V f results...……………..……………………………… 220<br />

xvi


LIST <strong>OF</strong> ABBREVIATIONS<br />

2D<br />

3D<br />

ASTER<br />

DCW<br />

DED<br />

DEMs<br />

DLG<br />

DTD<br />

DTM<br />

EOS<br />

ETM+<br />

GCPs<br />

GIS<br />

GPS<br />

JDT<br />

JDTZ<br />

JSO<br />

RMSE<br />

S mf<br />

TPs<br />

USGS<br />

UTM<br />

V f<br />

WGS<br />

Two Dimensional<br />

Three Dimensional<br />

Advanced Spaceborne Thermal Emission and Reflection Radiometer<br />

Digital Chart of the World<br />

Digital Elevation Data<br />

Digital Elevation Models<br />

Digital Line Graph<br />

Digital Terrain Data<br />

Digital Terrain Model<br />

Earth Observing System<br />

Enhanced Thematic Mapper Plus<br />

Ground Control Points<br />

Geographic Information Systems<br />

Global Positioning System<br />

Jordan-Dead Sea Transform<br />

Jordan-Dead Sea Transform Zone<br />

Jordan Seismology Observatory<br />

Root Mean Square Error<br />

Mountain Front Sinuosity<br />

Tie Points<br />

The United States Geological Survey<br />

Universal Transverse Mercator<br />

Valley Floor Width to Valley Height Ratio<br />

World Geodetic System<br />

KEYWORDS: ASTER imagery, digital elevation model, geographic information<br />

systems, geomorphic indices, geomorphic analysis, Jordan, Jordan-Dead Sea<br />

Transform Zone (JDTZ), morphometric analysis, mountain front sinuosity, satellite<br />

remote sensing, tectonic geomorphology, valley floor width to valley height ratio.<br />

xvii


1. Chapter One: Introduction<br />

1.1. Research objectives<br />

The objective of this research is to develop a digital remotely sensed approach to<br />

characterize mountain front geomorphic form along the Jordan-Dead Sea Transform<br />

Zone (JDTZ) to assess the current degree of tectonic activity and achieve detailed<br />

analysis of the mountain front’s potential as an indicator of seismic activity.<br />

1.2. Research problem<br />

The relationship between earthquakes and faulting was examined by Allen<br />

(1975). In his research conducted in California, using the San Andreas fault system as an<br />

example, he indicated that nearly all large earthquakes with magnitudes greater than 6.0<br />

on the Richter Scale have occurred along existing faults that are associated with active<br />

mountain fronts. Such earthquakes occur at relatively shallow depths (less than 20km)<br />

that are largely associated with subsurface rupture and surface faulting and folding. In<br />

addition, he reported that larger earthquakes have generally occurred on the larger and<br />

longer faults (Allen 1975).<br />

Many studies around the world (Ganas et al. 2001, Tramutoli et al. 2001)<br />

confirmed the strong relationship between active faults and earthquakes and the<br />

usefulness of remote sensing techniques to recognize and analyze that relationship<br />

(Dreger and Kaverina 2000, Karnieli et al. 1996, Sabins 1997, Süzen and Toprak 1998).<br />

Such studies established that tectonism has a geomorphic expression in regions where it<br />

occurs (Gerson et al. 1984).<br />

In Jordan, the primary seismic and tectonic zones are the Dead Sea fault system,<br />

and secondarily the Wadi Araba fault, including the Gulf of Aqaba region (Bender 1974a,<br />

1


Degg 1990, Yücemen 1992). Within the Jordan-Dead Sea Transform (JDT), the majority<br />

of the historical and the 20 th<br />

century instrumental recorded earthquakes, often<br />

accompanied with crustal deformation, are clustered on these two fault systems that are<br />

believed to be associated with active mountain fronts (Abou Karaki 1995, Al-Tarazi<br />

1992, Arieh and Rotstein 1985, Ben-Avraham et al. 2005, Ken-Tor et al. 2001, Klinger et<br />

al. 2000a, 2000b, Olimat 2001) (figure 1.1).<br />

Figure 1.1: Earthquakes in the Jordan-Dead Sea Transform and adjacent areas, 1900-<br />

1980 (Modified from Arieh and Rotstein 1985, figure 3, P. 884).<br />

2


The largest earthquake recorded in the Gulf of Aqaba was on November 22, 1995<br />

and had a moment magnitude of 7.3 and a local magnitude of 6.2 on the Richter Scale<br />

with a depth of 14km and an epicenter off-shore about 60km from the head of the gulf<br />

where the cities of Aqaba and Elat are located (Al-Tarazi 2000, Klinger et al. 1999). This<br />

earthquake was the beginning of a seismic swarm that occurred in the central part of the<br />

Gulf of Aqaba. During this swarm, the Jordan Seismology Observatory (JSO) detected<br />

2,089 earthquakes with magnitudes ranging between 2.0 to 6.2, which strongly affected<br />

the near-shoreline cities (Al-Tarazi 2000).<br />

More recently, on September 9, 2006 at 7:58 am, an earthquake with a local<br />

magnitude of 4.5 on the Richter Scale struck the northern part of the Dead Sea with an<br />

epicenter depth of 7.7km (Zgheylat 2006a). On September 18, 2006 near noon time,<br />

another earthquake with a local magnitude of 4.2 on the Richter scale was detected in the<br />

exact location as the previous quake with an epicenter depth of 7km (Zgheylat 2006b).<br />

Both earthquakes were associated with the natural intersection of the River Jordan and<br />

Al-Zarqa Faults (Zgheylat 2006a, 2006b). Earlier, on January 23, 2005, an earthquake of<br />

local magnitude 3.5 on the Richter Scale occurred in the northern Dead Sea segment, one<br />

of a series of two other quakes with local magnitudes of 2.7 each in the Dead Sea and<br />

Tiberias Lake (also known as the Sea of Galilee or Lake Kinneret). The hypocenters of<br />

the quakes were believed to be a few tens of kilometers below the northern section of the<br />

Dead Sea level (Abu El-Zelouf 2005).<br />

In a similar incident, an earthquake with a magnitude of 4.9 on the Richter Scale<br />

struck Jordan on Wednesday, February 11, 2004. The quake occurred at 11:14am and<br />

lasted for around 20 seconds. The hypocenter was located to the northeast of the Dead<br />

3


Sea with a depth of 20km. The main quake was followed by seven aftershocks with<br />

magnitude of two to three points on the Richter Scale (Husseini 2004). The Jordan<br />

Seismology Observatory in the Dead Sea area detected five seismic events on December<br />

31, 2003 and January 1, 2004. The five earthquakes had maximum magnitudes of 3.8 on<br />

the Richter Scale. Such quakes are considered normal, weak, and occur frequently in this<br />

area. The first quake was recorded at 1:30pm with a magnitude of 3.3 on the Richter<br />

Scale. The strongest quake had a local magnitude of 3.8 while the others recorded 2.5<br />

each, with a depth range of 19 to 8.5 kilometers (Al-Gharaibeh 2004).<br />

Five large earthquakes with a local magnitude of 6.0 or higher are recorded for<br />

the region between the Dead Sea and the Gulf of Aqaba. These include the earthquakes of<br />

A.D. 1068, 1202, 1212, 1293, and 1458 (Ellenblum et al. 1998, Niemi et al. 2001). The<br />

epicenters of the 1068 and 1212 quakes were probably in the southern Araba Valley<br />

(Niemi et al. 2001). Clearly, the occurrence of earthquakes represents a significant<br />

geologic event in the region, with potential significance for the associated human<br />

population.<br />

1.3. Justification of the Study<br />

This study is believed to be the first attempt to apply two geomorphic indices,<br />

namely mountain front sinuosity (S mf ) and valley height to valley floor width ratio (V f ) to<br />

conduct morphometric analysis in the Jordan-Dead Sea Transform zone. Since these<br />

geomorphic indices were first introduced as indicators of seismic activity (Bull and<br />

McFadden 1977), normally all measurements have been collected using topographic and<br />

geologic maps as sources of elevation then manually calculated to determine the indices<br />

values. In this research a new methodology is applied using a digital approach, including<br />

4


satellite imagery, multiple layers of geographic data, and digitized calculations of the two<br />

geomorphic indices of seismic potential to achieve more precise determinations.<br />

Previous studies focused on the Jordan-Dead Sea Transform, including the Dead<br />

Sea and Wadi Araba, employed different analytical techniques and multiple sensors in<br />

their applications, including Landsat TM (Gerson et al. 1984, Malkawi et al. 2000),<br />

Radarsat (Abdelhamid 2001), SPOT imagery and SPOT derived DEM (Klinger et al.<br />

2000a, 2000b), GTOPO30 dataset (Galli and Galadini 2001), digitized topographic maps<br />

(Hall 1997), gravity anomaly maps (Brink et al. 1999), plus paleoseismic analyses<br />

(Marco et al. 2005, Zilberman et al. 2000), GPS geodesy (Wdowinski et al. 2004), and<br />

seismic anisotropy (Rümpker et al. 2003).<br />

This study aims to accomplish the transition from a conventional to digital<br />

morphometric analysis approach in order to determine tectonic activity along the<br />

mountain fronts in the Jordan-Dead Sea Transform Zone (JDTZ) to examine their degree<br />

of activity and add to the repertoire of geomorphic and environmental studies in Jordan.<br />

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)<br />

imagery will be the main source of Digital Elevation Models (DEMs) and an input to<br />

other digital data. Morphometric analysis is being utilized because the results of this<br />

method have proven to be reliable and relatively accurate in the assessment of tectonic<br />

activity of large-scale regional analysis of natural geomorphic forms (Azor et al. 2002,<br />

Silva et al. 2003, Zovoili et al. 2004). In addition, this approach is easy, does not require<br />

expensive equipment, and can be remotely performed without conducting field<br />

measurements.<br />

5


1.4. The Jordan-Dead Sea Transform Zone characteristics<br />

The following section is a brief description of the geomorphology, geology, and<br />

seismicity of the Jordan-Dead Sea Transform zone. Several seismic maps of Jordan and<br />

its vicinity are included to illustrate the relationship between tectonic events and major<br />

faults along the JDTZ, such as earthquakes in Jordan and the surrounding countries,<br />

seismic zones in the area, and the major fault lines located in Jordan.<br />

1.4.1. Geomorphology of the JDTZ<br />

The study area extends from the northern shoreline of the Dead Sea Transform<br />

System, Wadi Araba (Araba or Arava Valley), to the Gulf of Aqaba. The focus is on the<br />

eastern portion of the region that falls only within the Jordanian territories defined by<br />

Jordan’s western borders. Since the study area is part of the Jordan-Dead Sea Rift system<br />

(Dead Sea Transform System, DST) and the Jordan-Wadi Araba Rift including the Gulf<br />

of Aqaba area, it will be referred to as the Jordan-Dead Sea Transform Zone (JDTZ). The<br />

JDTZ extends approximately 245km in length (N-S direction) and about 40km in width<br />

(E-W direction), as illustrated in figure 1.2.<br />

6


Figure 1.2: Jordan-Dead Sea Transform Zone (JDTZ) dimensions; 245km (N-S) and 40<br />

km (E-W).<br />

7


The Jordan-Dead Sea Rift system, that contains the JDTZ, extends over 1,000km,<br />

which is a portion of the original 6,000km East African-North Syrian Fault System that is<br />

also called the East Africa-Asia Rift System (Bender 1974a, 1975, Burdon 1959, Klinger<br />

et al. 2000a) (figure 1.3). The Rift margins show extensive extensional rifts combining<br />

normal faults and flexures. The movement along the Dead Sea Transform began in the<br />

early Miocene during two stages of left-lateral displacement and counterclockwise<br />

rotation of the Arabian plate relative to the African plate (Goudie 2002, Taqieddin et al.<br />

2000), as shown in figure 1.4. This has led to the formation of several pull-apart basins<br />

and push-up swells along the transform. The Dead Sea Basin is the deepest and largest<br />

pull-apart basin along the Jordan-Dead Sea Rift system with active seismicity along the<br />

transform area (Bender 19974b, Niemi et al. 2001, Taqieddin et al. 2000).<br />

Figure 1.3: East African Rift System (Modified from Keller and Pinter 2002, figure 2.17,<br />

p. 69).<br />

8


The Red Sea is essentially a spreading center between the Arabian and Nubian<br />

plates (Garfunkel 1997). Since is it located to the south of the Gulf of Aqaba, the latter is<br />

directly affected by any tectonic activity in the Red Sea. The motion between the Arabian<br />

and Nubian plates is parallel to the total motion of the Red Sea transform (Sultan et al.<br />

1993).<br />

Figure 1.4: Tectonic setting of the Middle East. Arrows show the motion between the<br />

Arabian and African Plates along the Dead Sea Fault (DSF), the North Anatolian Fault<br />

(NAF), and (EAF) East Anatolian Fault (Modified from Goudie 2002, figure 8.1, p. 216).<br />

The breakup of the continuous Afro-Arabian continent during the Cenozoic Era<br />

and the successive drift of Arabia from Africa created a series of rifts reflected by major<br />

morphologic depressions. The Dead Sea rift is mainly a transform boundary, while the<br />

9


Red Sea which is the longest and biggest basin within the Rift system has developed<br />

through a stage of continental extension and is now a spreading boundary (Joffe and<br />

Garfunkel 1987). In fact, most of the spectacular relief and structures in the Middle East<br />

and northeastern Africa are related to the tectonic movements resulting from the opening<br />

of the Red Sea basin (2000km long and 350km wide) that started in the Late Oligocene<br />

about 30Myr (Goudie 2002) (figure 1.5).<br />

Figure 1.5: (A) Wadi Araba Valley location map along the Jordan-Dead Sea Transform<br />

fault system (JDT). (B) Generalized geologic map of Wadi Araba Valley showing<br />

location of selected major active faults and juxtaposition of different bedrock lithologies<br />

across the valley (Modified from Niemi et al. 2001, figure 1, p. 450).<br />

10


Wadi Araba extends about 147km in length (Niemi et al. 2001) and is part of this<br />

depression that is located between the Gulf of Aqaba and the Dead Sea to the northnortheast.<br />

The transform fault strikes N15˚E - N5˚E (Bender 1974b, 1975, 1982). The rift<br />

valley rises gradually from the Gulf to an altitude of about 250m at the watershed of Jebel<br />

er-Risha (75-80km long) and continues about 1,000m from this divide to the southern<br />

shore of the Dead Sea where it decreases to an altitude of 400m-409m below sea level<br />

(Andrews 1996, Bender 1974b, 1975). The width of the valley averages 15km but varies<br />

significantly between 9km at the narrowest part in the south about 16km NNE of Aqaba,<br />

to about 25km in the north at Wadi Feinan (Bender 1974b, 1975, Niemi et al. 2001).<br />

Unconsolidated sediments of Quaternary age and older clastic sediments occupy most of<br />

the Wadi Araba floor (Bender 1974b, 1975, 1982).<br />

The Wadi Araba-Jordan Valley is a transform valley and is distinguished from rift<br />

valleys that are bound by normal faults and escarpments on both sides by having a strikeslip<br />

fault that trends at an angle to the transform valley (Ginat et al. 1998). The highlands<br />

bordering the east side of the Jordan rift valley rise 1,592m in the south at Jebel er-Risha,<br />

about 1,500m above the valley floor, and 1,200m in the north at the east side of the<br />

southern end of the Dead Sea about 1,550m above the level of the Dead Sea (Bender<br />

1974b, 1975). The mountain ridge east of the rift slopes gently eastward in the direction<br />

of the central plateau, while it is very steep on its western side towards the rift where it<br />

reaches 1,734m in height (Bender 1974b, Royal Geographic Center 1992). Many wadis<br />

and perennial streams cut farther eastward into the plateau capturing additional area in<br />

the drainage basins of the rift (Bender 1974b, 1975, 1982).<br />

11


Both the western and eastern sides of the rift valley demonstrate distinct, mostly<br />

triangular-shaped morphological projections and niches of structural origin (Bender<br />

1974b), which could reflect the disharmonic faulting in the Jordan-Wadi Araba graben<br />

(Picard 1952). The eastern scarp of the Dead Sea basin in Jordan is relatively straight and<br />

continuous and is bounded by a single bordering fault (figure 1.6), whereas, the western<br />

side, located in Israel, is more complex with several step faults or fault splinters involved.<br />

Left lateral movement along a curved strike-slip fault is believed to have opened the<br />

Dead Sea pull-apart basin (Bartov and Sagy 2004, Goudie 2002).<br />

Figure 1.6: Block diagram along the central part of the JDTZ illustrating the tectonic<br />

style and the continuous rise of the graben floor (From Kashai and Croker 1987, figure<br />

11, p. 50).<br />

According to Picard (1987), the Aqaba (Elat)-Dead Sea-Jordan subgraben system<br />

(i.e. Jordan-Dead Sea Transform) is divided into four distinct subgrabens namely (1) The<br />

Gulf of Aqaba and South Araba, (2) The North Araba-Dead Sea-South Jordan, (3)<br />

12


Central Jordan Valley and Lake Tiberias, and (4) North Jordan or Hula Valley (figure<br />

1.7). The first two subgrabens are located within the JDTZ, therefore, a brief description<br />

of both geomorphology and geology are included below according to Picard (1987)<br />

interpretations.<br />

Figure 1.7: The Aqaba-Dead Sea-Jordan subgraben system (From Picard 1987, figure 1,<br />

p. 24).<br />

13


1) The Gulf of Aqaba (Elat) graben extends about 180km in length to Tiran, is 15-<br />

25km in width, and is up to 1,850m in depth. It is composed of Precambrian basement<br />

rocks and surrounded by the 2,000m high Sinai and Hedjaz horsts. The Sinai slopes are<br />

cut by Pliocene-Quaternary meridian (N-S) to submeridian (NNE-SSW) normal dip-slip<br />

faults that are sometimes coupled with minor strike-slip faults. Subgraben faults have an<br />

average dip of 70°. The mean width of the graben between the main marginal faults, now<br />

covered by the Red Sea, is 20km (Picard 1987).<br />

2) The North Araba-Dead Sea-South Jordan subgraben is north of the Aqaba-<br />

South Araba subgraben. The former subgraben is distinguished by a 700m altitude<br />

difference from the latter. It stretches roughly 80km in length from the Jebel er-Risha,<br />

watershed that consists of Paleocene-Eocene limestone and marls, down to the Dead Sea<br />

(400 below mean sea level). On the Jordanian (Transjordan) side, a large fault oriented<br />

NNE (20° to 25°) extends from Jebel er-Risha area and is masked by the Araba alluvial<br />

deposits (Picard 1987).<br />

The Jordan-Dead Sea Transform has several structural characteristics which have<br />

been highlighted by several scholars that can be summarized as follow:<br />

1) A major left-lateral offset of about 105-110km has taken place along a belt of<br />

strike-slip faults across the transform (Klinger et al. 2000b, Quennell 1959).<br />

Most of the movement was over by the Quaternary. The offset occurred across<br />

an area several kilometers wide near the Gulf of Aqaba (Picard 1987).<br />

2) Grabens are rhomb-shaped. They appear as depressions in the transform floor<br />

that were produced by strike-slip faults, many of which are en echelon (Picard<br />

1987, Quennell 1959), as shown in figure 1.8.<br />

14


3) Relief of several hundreds to a few thousands meters is present as a result of<br />

normal faulting along the transform margins. As a result, an apparent contrast<br />

between uplifted shoulders and downfaulted stepped blocks exist in a few<br />

locations along the transform margins (Picard 1987) (figure 1.9).<br />

Figure 1.8: A block diagram -not to scale- showing the strike-slip geometry along the<br />

JDTZ representing the en echelon fault system (From Kashai and Croker 1987, figure 15,<br />

p. 57).<br />

15


Figure 1.9: The Seven Pillars of Wisdom of southern Jordan developed on the Cambrian-<br />

Ordovician Sandstones in Wadi Rum located in the Aqaba area (Modified from Goudie<br />

2002, Plate 8.2, p. 227).<br />

1.4.1.1. Rifting Process and Extensional Tectonics<br />

The Jordan-Dead Sea Transform Zone is a rift valley that separates the two<br />

tectonic plates, the Arabian to the east and the African to the west. Rift valleys are<br />

significant landforms associated with continental crust where the lithosphere is<br />

dominated by tensional stress (Summerfield 1997, van der Pluijm and Marshak 1997)<br />

(figure 1.10).<br />

Figure 1.10: The East Africa Rift Valley as an example of the rifting process (From<br />

Keller and Pinter 2002, figure 2.16 (a), p. 68).<br />

16


The structure of rifts include complex normal faults of planar and listric patterns.<br />

The widely accepted and traditional view of the geomorphology of normal faults within a<br />

rift system shows downthrown blocks as grabens bounded by planar normal faults in<br />

which horsts repeat in a symmetric pattern (figure 1.11a). On the other hand, listric faults<br />

produce asymmetric structures with the downthrown block generating a half-graben<br />

structure (figure 1.11b) (Park 1988, Summerfield 1997, van der Pluijm and Marshak<br />

1997).<br />

Figure 1.11: Rift structure (A) symmetric horst and graben structure (B) Asymmetric<br />

listric fault half-graben structure (From Summerfield 1997, figure 4.9, p. 92).<br />

Normal faults in rift systems are generated by tensional tectonic forces due to the<br />

extension of lithosphere (i.e. crustal stretching) at divergent plate boundaries in the<br />

oceanic lithosphere (e.g. Mid-Atlantic Ridge) and in the continental lithosphere (e.g. East<br />

African Great Rift Valley) (Buck 1991, Park 1988, van der Pluijm and Marshak 1997). In<br />

17


most cases, normal faults are composed of parallel arrangements that might be planar or<br />

listric. The movement of a listric normal fault triggers rotation of the hanging wall around<br />

a horizontal axis which forms a rollover anticline. Along listric normal faults, the hanging<br />

wall sloping in the direction of the main fault generates half-graben depressions. This<br />

formation is widely seen in the Basin and Range of the southwestern United States<br />

topography where half-grabens form the basins and the tilted fault block forms the ranges<br />

(figure 1.12a). If normal faults happen in conjugates, planar normal faults will form. In<br />

this case, the block enclosed between them drops down creating a graben, while the<br />

remaining uplifted block to its side will form a horst (figure 1.12b) (Park 1988, van der<br />

Pluijm and Marshak 1997, Wernicke 1981, Wernicke and Burchfiel 1982).<br />

Figure 1.12: Normal fault system (a) Half-graben system (b) Horst and graben system<br />

(From van der Pluijm and Marshak 1997, figure 8.31, p. 173).<br />

The traditional concept of active asymmetric arrangements of horsts and grabens<br />

requires that at some point the displacement of faults will disappear or die out at depth.<br />

The models of asymmetric faulting in rift systems indicate that the listric normal faults<br />

merge at depth with a regionally extensive subhorizontal detachment fault (figure 1.13)<br />

18


(Price 1990, van der Pluijm and Marshak 1997, Wernicke 1981, Wernicke and Burchfiel<br />

1982).<br />

Figure 1.13: (a) Symmetric horst and graben system (b) Half-graben system above the<br />

subhorizontal fault detachment (From van der Pluijm and Marshak 1997, figure 15.5, p.<br />

326).<br />

The JDTZ is distinguished by its large alluvial fans that are normally found in arid<br />

to semiarid regions. Alluvial fans are considered to be an erosional-depositional system<br />

with a surface that has a cone-shape and concave cross-section. They spread out from the<br />

point where the stream leaves the mountain to form cone-shaped bodies. The fan slope is<br />

affected by the stream channel slope, width, and depth that changes discharge patterns<br />

and depositional patterns. All alluvial fans have only one apex (head), which is the<br />

attaching point with the mountain, and end at the toe (Bull 1968, 1977a, Bull and<br />

McFadden 1977, Summerfield 1997). The western side of the JDTZ margins is delimited<br />

by widespread alluvial fan bajadas, as illustrated in figure 1.14. The alluvial fans are<br />

deformed by fault displacement in the JDTZ (Baker 1986b, Rockwell et al. 1984,<br />

Summerfield 1997).<br />

19


Figure 1.14: Alluvial fans (bajadas) at the southern end along the eastern side of Wadi<br />

Araba (Left: Landsat 7 ETM+ 742-composite image; Right: Landsat 7 ETM+ Band-7 of<br />

the JDTZ, 2002).<br />

1.4.2. Structure and Geology of the JDTZ<br />

1.4.2.1. Structure<br />

1.4.2.1.a. Wadi Araba<br />

The Jordan Rift Valley, that includes the Wadi Araba fault, is the single most<br />

important structural feature that extends the whole length of the country and forms<br />

Jordan’s western border (Andrews 1996). The meridional rift valley forms a 200km long<br />

portion of the East African-North Syrian zone of structural weakness. The Wadi Araba<br />

fault system strikes N15°E from the Gulf of Aqaba to the Dead Sea and separates the<br />

Palestine Block in the west from the Transjordan Block in the east. In comparison with<br />

the Palestine block, the Transjordan block is structurally higher, has steeper regional dips<br />

to the north, and drops off more rapidly north of east-west fault zones (Bender 1974b,<br />

1975, 1982). The Wadi Araba fault system illustrates an obvious left lateral strike-slip<br />

fault system with a movement history primarily during mid Miocene and Pliocene-Recent<br />

phases (Andrews 1996, Bender 1975). This strike-slip movement has also led to the<br />

formation of discontinuous and irregular extensional grabens and compressional folds<br />

20


along its length (Andrews 1996). A study conducted by Burdon (1959) suggests that the<br />

tectonism of Jordan was divided into tensional and compressional structures. Several<br />

studies including Burdon’s, have determined five major compressional features in Jordan<br />

(30-80km long) primarily oriented in the NE-SW direction. These are the Wadi El-Yabis,<br />

Wadi Shueib, Biren, Amman-Al-Hallabat, and Al-Shawbak structures that are<br />

constructed of a series of folds and thrust faults (Al-Tarazi 1992). In general, continuous<br />

fault zones exist along both sides of the Jordan-Dead Sea Transform. All major active<br />

fault systems to the east of the rift strike at various angles to the direction of the Jordan-<br />

Dead Sea Transform (Bender 1974b, 1982), forming cliffs and causing occasional<br />

earthquakes in the area and its vicinity (Andrews 1996).<br />

Within the rift valley itself, the major faults are parallel to the direction of the<br />

Jordan-Dead Sea Transform. The network of faults dividing the mountain range east of<br />

the western border faults has the same trend as the border fault system; north, northnorthwest,<br />

northwest, and roughly east-west. The north-trending faults are much longer<br />

than the others. The faults parallel to the direction of Wadi Araba and to a larger scale to<br />

the Jordan-Dead Sea Transform have affected Miocene to Pliocene and Quaternary<br />

sediments within the rift valley. Along the border faults, significant dip-slip movements<br />

have occurred with the down-dropping of the western block often exceeding 500m<br />

(Bender 1974b, 1982).<br />

1.4.2.1.b. The Dead Sea<br />

The Dead Sea, often called the Dead Sea Rift or the Dead Sea Depression (DSD),<br />

is a transform feature between the Red Sea in the south and the collision zone of the<br />

Taurus-Zagros Mountains in the north (Freund 1965). The Dead Sea is about 100km long<br />

21


and 10-15km wide. Its catchment area has the capacity of 40,000km 2 of saline water<br />

(Arkin and Gilat 2000, Garfunkel 1997, Taqieddin et al. 2000). It is a major plate tectonic<br />

feature forming the boundary between the Arabian plate on the east and the African plate<br />

(Sinai subplate) on the west. It is considered a major strike-slip fault that has about<br />

100km of cumulative left-lateral slip. The Dead Sea is the lowest point on Earth (about<br />

400-415m below mean sea level) and it is one of the many basins along the Dead Sea<br />

Transform System that has up to 700m high escarpments. It developed as a wide pullapart<br />

basin containing fluvial and evaporite beds of Miocene to Holocene age about 20-<br />

25Myr to 10kyr (Frumkin 2001, Garfunkel 1997, Klinger et al. 2000a, Quennell 1983,<br />

Taqieddin et al. 2000). The Dead Sea is considered to be a transform depression rather<br />

than a rift because it is bounded by normal faults whose scarps reach 700m and are<br />

accompanied with left lateral strike slip (Zilberman et al. 2000).<br />

The Dead Sea consists of two basins, the northern and southern basins, which are<br />

divided by the Lisan Peninsula. The northern basin, which is larger and deeper, is about<br />

50-60km long and 700-730km below mean sea level. The southern basin is smaller and<br />

shallower, about 30-40km long and 300-350km below sea level, and is almost dry at the<br />

present time (Arkin and Gilat 2000, Garfunkel 1997, Goudie 2002, Taqieddin et al. 2000,<br />

Yechieli et al. 1998) (figure 1.15). The level of the Dead Sea has dropped 20m during the<br />

twentieth century (Arkin and Gilat 2000) with an average annual withdrawal rate of<br />

0.8m/yr (Yechieli et al. 1998). In recent years, the Dead Sea’s southern basin is almost<br />

dry due to mineral harvesting by Potash Companies both in Jordan and Israel. The<br />

northern basin contains saline water with a catchment capacity of about 40,000-<br />

42,000km 2 (Garfunkel 1997, Yechieli et al. 1998).<br />

22


A<br />

B<br />

Figure 1.15: (A) Dead Sea location map showing the two basins (From Arkin 2000,<br />

figure 2, p. 713). (B) Inset map shows the present watershed of the DSD and the general<br />

location of major strike-slip faults along the Dead Sea transform. The DSD is enlarged<br />

showing its flanked escarpment associated with normal faulting along the depression<br />

border (From Frumkin 2001, figure 1, p. 80).<br />

1.4.2.2. Geology<br />

The geology of the Jordan-Dead Sea Transform Zone includes the youngest rocks<br />

(i.e. lake sediments) to be found in Jordan. In general, these rocks were deposited 15000<br />

years ago after extensive lakes diminished during the Late Pleistocene, which occupied<br />

the whole area forming soft siltstones and mudstones. Such rocks have been eroded into a<br />

landscape of gullies and cliffs (Andrews 1996, Ron et al. 2006). Along the fault systems,<br />

younger rocks are down-faulted against older complexes to the east, forming the<br />

23


triangular shaped structural niches, giving the east side of the Jordan-Dead Sea<br />

Transform its distinct structure and morphological characteristics (Bender 1974b, 1982).<br />

The JDTZ, especially Wadi Araba, is occupied entirely by unconsolidated<br />

sediments of Quaternary age and older clastic sediments and limestones. Pre-Cambrian<br />

igneous and metamorphic rocks cover an area of approximately 1,800km 2 in southern<br />

Jordan. These rocks are exposed from the area south of Aqaba for approximately 70km<br />

towards the north along the east side of the Wadi Araba Rift. They are also exposed east<br />

of the Rift and south of the Ras en-Naqab escarpment, dipping east of Wadi Rum<br />

underneath a thick sequence of Paleozoic sandstones (Bender 1974a, 1975, Burdon 1959)<br />

(figure 1.16).<br />

Figure 1.16: Jordan-Dead Sea Fault simplified geological cross-section. (Pε)<br />

Precambrian, (P) Paleozoic, (K) Cretaceous, (E) Eocene, (M) Miocene, and (PL) Pliocene<br />

rocks and sediments (From Ginat et al. 1998, figure 3, p. 154).<br />

The Jordan-Dead Sea Transform Zone basement is mainly divided into the Aqaba<br />

and the Araba complexes separated by a regional unconformity, where the former<br />

complex consists of two units and the latter consists of three units. Figure 1.17 is a<br />

24


simplified geological cross section across the southern section of the Jordan-Dead Sea<br />

Transform near Al-Quwayra town which is located about 35km northeast of Aqaba (Sneh<br />

et al. 1998).<br />

Figure 1.17: A simplified geological cross section across the southern section of the<br />

Jordan-Dead Sea Transform, about 40km northeast of Aqaba (Modified from Sneh et al.<br />

1998).<br />

1.4.2.2.a. The Aqaba Complex<br />

1) Metamorphic Rocks: The metamorphic rocks are found as blocks within the<br />

surrounding Neoproterozoic intrusive rocks. In Wadi Abu Burqa, at Gharandal area, they<br />

were preserved from erosion before deposition of the Cambrian rocks. The metamorphic<br />

rocks are dated as 700-800Myr (Jarrar et al. 1983). This age matches the age obtained for<br />

the metamorphic rocks of the Elat area (Kroner et al. 1990).<br />

2) Igneous Rocks: The igneous rocks consist of highly weathered granites,<br />

granodiorites, and quartz diorite. The plutons of the Aqaba complex have an average age<br />

of 630-580Myr (Ibrahim and McCourt 1995).<br />

1.4.2.2.b. The Araba Complex<br />

1) Sarmuj Conglomerates: The Sarmuj conglomerates occur in very small<br />

outcrops along the lower course of Wadi Abu Burqa, with an exposed thickness of about<br />

40m. They form the base of the Araba complex (Bender 1974a). The unit consists of<br />

25


conglomerates with well rounded clasts of plutonic and metamorphic rocks in a partly<br />

brecciated and arkosic-sandy matrix. The base of the Sarmuj conglomerates is<br />

distinguished by the age of the underlying calc-alkaline granitoids and is dated at 625-<br />

600Myr (Jarrar 1985).<br />

2) Hayyala Volcaniclastic Unit: The volcaniclastic unit is a series of stratified,<br />

steeply east dipping, green weathering tuffs with thin horizons of volcaniclastic<br />

sandstone. They are exposed in the margin of Wadi Araba and overlain with an angular<br />

unconformity by Cambrian sedimentary rocks (Bender 1974a). This unit is believed to be<br />

Late Neoproterozoic in age, dated between 595-550Myr (Ibrahim 1993).<br />

3) Rhyolite Volcanics: The upper part of the rhyolite is highly weathered and cut<br />

by dykes and has intrusive joints that are overlain by Cambrian sandstones. This unit was<br />

first recognized in Wadi Rum and believed to be 550-542Myr in age (McCourt and<br />

Ibrahim 1990).<br />

1.4.2.2.c. The Dead Sea<br />

The Dead Sea floor is covered by Neogene and Quaternary sediments up to<br />

several kilometers thick (Picard 1987). Several studies confirmed that the Dead Sea basin<br />

was found to have 10km of sediments with ages from the Neogene to the present time<br />

(Garfunkel 1997, Niemi 1997). According to Frumkin (2001), the macrostratigraphic<br />

analysis of the sediment that has been recovered from the Cave of the Letters in Israel<br />

(west of the transform) indicates a low deposition of the Dead Sea basin around 10-7Myr<br />

ago.<br />

The early formation of the Dead Sea rift took place at some stage in the<br />

Oligocene. During the Miocene it developed as an elongated sedimentary basin with<br />

26


primarily clastic and some volcanic input from the Oligocene to the Pleistocene, salt<br />

lakes and evaporite deposits were formed, creating the present day Dead Sea. Clastic,<br />

evaporite, alluvial, and lacustrine sediments continued to be deposited throughout the<br />

Pleistocene until today (Arkin and Gilat 2000, Klinger et al. 2000a).<br />

A brief geological description of the rock types and their abundance within the<br />

JDTZ are listed in table 1.1 illustrating the location of the examined mountain fronts and<br />

their proximity to different rock types that consequently will affect the final<br />

morphometric analysis results. Harder rocks (e.g. limestone) are primarily located in the<br />

northern region while mostly softer and weathered rocks (e.g. sandstone), with an<br />

exception to the presence of a small number of fronts along granite mountains, are<br />

present in the southern region, as shown in figure 1.18.<br />

27


Location Rock Type Description<br />

Q 4<br />

Lisan Formation (Jordan Valley) deposited in a lacustrine<br />

environment during the Quaternary that consists of sandstone,<br />

shale, chalk, marl, and conglomerate<br />

βq<br />

Little quantities of olivine basalt, scoria, tuff, and agglomerate<br />

(Quaternary, younger than 1.8Myr)<br />

Dead Sea<br />

Limestone, chalk, chert, marl, and clay (Senonian-Paleocene)<br />

North<br />

Araba<br />

South<br />

Araba<br />

Aqaba<br />

K S<br />

β1<br />

Ja<br />

Q 4<br />

T S<br />

K J<br />

P Mn<br />

Q<br />

P Mn<br />

Q<br />

K K<br />

P Mn<br />

G C<br />

Magmatic intrusions of alkali basalt (Jurassic-Lower Cretaceous:<br />

few scattered quantities within the Lisan Formation)<br />

Limestone, dolomite, and sandstone (Upper Zarqa Group, Jurassic)<br />

Lisan Formation (Jordan Valley) deposited in a lacustrine<br />

environment during the Quaternary that consists of sandstone,<br />

shale, chalk, marl, and conglomerate<br />

Limestone, clay, marl, gypsum, and conglomerate (Late Eocene-<br />

Pliocene)<br />

Limestone, dolomite, and marl (Late Cretaceous: Cenomanian-<br />

Turonian)<br />

Sandstone (little quantity) mainly with existence of clay and<br />

dolomite (Cambrian-Turonian)<br />

Undifferentiated Alluvium (Quaternary), most abundant bedrock<br />

Sandstone mainly with existence of clay and dolomite (Cambrian-<br />

Turonian)<br />

Undifferentiated Alluvium (Quaternary), most abundant bedrock<br />

Sandstone: massive and brownish weathered sandstone (Lower<br />

Cretaceous)<br />

Sandstone mainly with existence of clay and dolomite (Cambrian-<br />

Turonian)<br />

Granite: gray granite and alkali granite (Precambrian)<br />

Table 1.1: Concise description of the mountain fronts rock types within the JDTZ<br />

(Modified from Bartov 1990 and Bender 1974b).<br />

28


Figure 1.18: Rock types and the locations of all mountain fronts in the JDTZ study area.<br />

29


1.4.3. Seismicity of the JDTZ<br />

1.4.3.1. Regional tectonics of Jordan and its vicinity<br />

The Levant is a unique region in terms of documenting historical earthquakes that<br />

covers the time span of four millennia. This documentation is in a variety of forms that<br />

includes biblical, Roman ecclesiastical, and Islamic and Arabic historical chronicles.<br />

During the last 4,000 years, several destructive earthquakes occurred over large areas of<br />

the Middle East region that caused loss of life and property (Abou Karaki 1995, Al-<br />

Tarazi 1992, Degg 1990). A thorough analysis of the earthquakes that affected Northwest<br />

Arabia (modern Jordan, Palestine, and Israel) from the 2 nd to the mid-8 th century A.D.<br />

was conducted by Russell (1985) from historical records and archaeological evidence<br />

collected in these countries. Destructive earthquakes occurred during the late Roman,<br />

Byzantine, and Early Islamic periods in Northwest Arabia, and were generated as a result<br />

of the existence of border faults and other structural elements along the rift valley that are<br />

capable of producing seismic activity (Russell 1985).<br />

The tectonism of Jordan is directly related to the regional tectonism in the Middle<br />

East and the Eastern Mediterranean region, which is mainly controlled by the Jordan-<br />

Dead Sea Transform fault system (Al-Tarazi 1992). Much of Jordan is subject to a<br />

momentous seismic threat that has been reported in contemporary geological and<br />

seismological investigations and also mentioned throughout ancient documents. During<br />

the past 80 years, seismic activity in Jordan has been relatively low; however, the whole<br />

region has been affected by earthquakes for thousands of years. An excellent example is<br />

the 1927 earthquake with a local magnitude of 6.25 on the Richter scale, which was<br />

devastating in several locations (Arieh et al. 1982, Avni et al. 2002, Ben-Menahem 1991,<br />

30


Marco et al. 1996, Niemi and Ben-Avraham 1994, Vered and Striem 1977). The main<br />

concern is that the major Jordanian cities and highly populated regions such as Amman,<br />

Irbid, Salt, Aqaba, Jarash, Al-Karak, Al-Mafraq, Al-Tafila, Ghour es-Safi, and Petra are<br />

located in earthquake-prone areas within proximity of active fault systems that branch off<br />

the JDT such as Carmel, Al-Karak, Al-Fiaha, Wadi El-Sirhan, Zarqa Main, and Swaqa<br />

faults (Abou Karaki 1995, Klinger et al. 2000b, Olimat 2001, Quennell 1958, Yücemen<br />

1992). Obviously, the most populated areas within this region are vulnerable to strong<br />

earthquakes, generating a real threat to the safety of population, infrastructure, social<br />

integrity, and economics of Jordan and its surrounding countries (Olimat 2001).<br />

The strongest earthquake activity zone in terms of magnitude and frequency is the<br />

Jordan-Dead Sea Transform fault system, which is considered an active tectonic feature<br />

based on the region’s seismicity (Yücemen 1992). The seismicity of Jordan-Dead Sea<br />

Transform system is considered to be low to moderate; nevertheless, several destructive<br />

earthquakes have occurred in the past that destroyed most of the urban areas in Jordan<br />

and the surrounding countries such as those in A.D. 362, 748, 1033, 1034, 1070, 1182,<br />

1201, 1759, 1837, 1927, 1956, 1995 (Al-Tarazi 1992, Olimat 2001).<br />

The primary seismic and tectonic threat in Jordan is derived from the Dead Sea<br />

fault system, and secondarily the Wadi Araba fault (Bender 1974a, Yücemen 1992).<br />

Paleoseismic analysis of the Azaz fault segment of the Dead Sea Rift indicates that this<br />

region was subjected to irregular periods of strong seismicity and quiescence during the<br />

latest Pleistocene and the Holocene. At least two large earthquakes occurred in the Early<br />

Holocene, each one resulting in a 1-1.5m high fault scarp (Zilberman et al. 2000). In a<br />

recent study, paleoseismic analysis of the Bet-Zayda Valley in the delta of the Jordan<br />

31


River at the north shore of the Sea of Galilee along the Dead Sea Transform exposed<br />

several stream and surface offsets as a result of the earthquakes that occurred in the area.<br />

The three-dimensional excavations of buried stream channels at Bet-Zayda demonstrate<br />

primarily strike-slip displacement at a minimum rate of 3mm/yr during the Late Holocene<br />

(Marco et al. 2005).<br />

The displacement along the Jordan-Dead Sea Transform was measured from the<br />

displacement of several alluvial fans within the transform. For example, the study of the<br />

Dahal area along Wadi Dahal fault revealed an offset of the largest alluvial fan (i.e. Dahal<br />

fan). The average slip rate of the Dead Sea fault is 4±2mm/yr, corresponding to about<br />

500m of offset since the last interglacial period, consistent with the relative motion<br />

between Arabia and Africa and regional kinematics measured by other techniques<br />

(Klinger et al. 2000a) such as the GPS data north of the Dead Sea (Pe’eri et al. 1998) and<br />

in northern Arabia (Reilinger et al. 1997, Pe’eri et al. 1998), the satellite laser ranging<br />

(SLR) measurements in Israel (Smith et al. 1994), and the data from the offset Plio-<br />

Pleistocene alluvial terraces analysis in the Wadi Araba (Ginat et al. 1998).<br />

In a similar study, Niemi et al. (2001) measured cumulative displacement of 22-<br />

54m from stream channels and alluvial fan surfaces across the Wadi Araba fault using<br />

detailed geologic and topographic mapping. The northern Wadi Araba fault maintained a<br />

relatively constant slip rate in the past 15kyr. The average slip rate of 4.7±1.3mm/yr was<br />

measured from offset fault-scarp alluvial fans. The cumulative displacement as a result of<br />

the last M W 7 earthquake was 3m. Using an average slip rate of 4.7±1.3mm/yr together<br />

with a 3m slip-per-event suggests a maximum earthquake recurrence interval for M L 7<br />

events of Wadi Araba fault of 500-885 years (Niemi et al. 2001). The total displacement<br />

32


along the Jordan-Dead Sea Transform (JDT) caused by left-lateral strike-slip is 107km.<br />

The left-lateral displacement along the JDT occurred in two steps: (1) 62km offset by<br />

Early Miocene (about 18Myr), and (2) 45km offset since the Late Miocene or Pleistocene<br />

to the present time (Niemi et al. 2001). The rotation rate of the Arabian plate was found<br />

to be 0.396˚Myr -1 around a pole at 31.10˚N, 26.70˚E relative to Africa (Klinger et al.<br />

2000a, Quennell 1983).<br />

Regional seismicity studies in Wadi Araba and the Dead Sea fault systems reveal<br />

much information regarding their activity and contribution to historical earthquakes in<br />

Jordan, Palestine and Israel. In an attempt to shed view on the anatomy of the regional<br />

plate boundary, a new gravity anomaly map of Wadi Araba and the southern half of the<br />

Dead Sea transform was produced by Brink et al. (1999) as shown in figure 1.19. The<br />

map highlights a string of numerous subsurface basins of various length, size, and depth<br />

along the plate boundary and relatively short (25 to 55km) and discontinuous fault<br />

segments that occupy the whole transform. Such structure suggests a dynamically<br />

changing plate boundary with time with continuous small changes in relative plate<br />

motion (Brink et al. 1999).<br />

1.4.3.2. Seismotectonic maps of Jordan<br />

The earthquake events that occurred in Jordan and the surrounding countries<br />

between 19A.D. and the end of the year 2005 indicate a significant concentration along<br />

the Jordan-Dead Sea Transform Zone. However, the collected seismic events show a<br />

lower concentration in the eastern part of the Mediterranean Sea when compared to the<br />

earthquake distribution of the major tectonic features in Jordan-Dead Sea Transform area.<br />

According to Al-Tarazi (1992) and based on several earlier studies conducted by Abou-<br />

33


Karaki (1987), Arieh (1991), Ben-Menahem (1979, 1981), Ben-Menahem et al. (1982),<br />

El-Isa and Al-Shanti (1989), and Poirier and Taher (1980), thirteen seismic zones were<br />

identified in Jordan and the surrounding countries of the Middle East. Below is a brief<br />

description of the seismic zones as shown in the seismotectonic map of Jordan and its<br />

vicinity (figure 1.20A) (Al-Tarazi 1992):<br />

Figure 1.19: Bouguer gravity anomaly map of Dead Sea transform, Jordan and Israel,<br />

corrected with density of 2670 kg/m 3 . Contour interval is 3 mGal. Terrain correction was<br />

calculated from digital terrain model (DTM) with 25m grid using inhouse code.<br />

Background: Shaded relief topography from DTM. Top inset is simplified plate geometry<br />

and location of maps. Bottom inset is a regional Bouguer gravity map of Israel and<br />

Jordan (From Brink et al. 1999, figure 1).<br />

34


1. Dead Sea-Jordan River fault (zones 1 and 2): It extends about 200km from 30.90º<br />

to 32.93ºN at a longitude of 35.50ºE that stretches from the Dead Sea along<br />

Jordan River and ends at Tiberias Lake in the north. This fault is characterized by<br />

high seismic activity. Many historical earthquakes occurred along its length. Also,<br />

earthquake epicenters occur along several active faults that branch from the main<br />

fault (figure 1.21).<br />

2. Wadi Araba fault (zone 3): It extends about 174km from the Dead Sea to the Gulf<br />

of Aqaba. The historic earthquake activity along this fault indicates that this fault<br />

is seismically less active than the Jordan-Dead Sea fault.<br />

A<br />

B<br />

Figure 1.20: (A) the thirteen seismic zones and (B) major faults within seismic zones in<br />

Jordan and its vicinity (From Al-Tarazi 1992, map 2.13, p. 49 and map 2.17, p. 53,<br />

respectively).<br />

35


3. The faults of the northern zone (zone 4): The northern zone extends from 30.93º<br />

to 35.00ºN and includes the Ed-Damur, Yammouneh, and Rachaya faults. The<br />

historic earthquakes show that this zone used to be more seismically active than<br />

the Jordan-Dead Sea fault but became less active with time.<br />

4. The faults of the northern Red Sea and the Gulf of Aqaba (zones 5, 6, and 7): The<br />

Red Sea Fault system includes both the faults of the Gulf of Aqaba and the Suez<br />

Gulf that are characterized by seismic swarm activity. However, the seismicity of<br />

the Gulf of Aqaba and the Red Sea zone is lower than of the Jordan-Dead Sea<br />

fault as indicated from the recorded earthquakes.<br />

5. The Wadi El-Sirhan Basalt Area (zone 8): This zone is located to the east of the<br />

Jordan-Dead Sea Transform. It is completely covered by basaltic material and<br />

characterized by slight seismicity.<br />

6. The Wadi Farah-, Carmel-, and Al-Galiel-zones (zones 9, 10, and 11): These three<br />

faults are considered secondary faults that are located to the west of the Jordan-<br />

Dead Sea Transform. The Wadi Farah fault seems to be active compared to the<br />

Carmel and Al-Galiel faults that are less seismically active. Most of the seismic<br />

activity in these faults occurs in swarms that never produced a historic devastating<br />

earthquake. However outlining them is essential as they are situated in a very<br />

densely populated area.<br />

7. The South-East Mediterranean zone (zone 12): This seismic zone was delineated<br />

based on the instrumental earthquake data recorded from this area. The seismic<br />

activity in this zone seems to be low and shallow in comparison to the Jordan-<br />

Dead Sea Transform zones.<br />

36


8. The Cyprus zone (zone 13): It covers the major earthquakes in and around Cyprus<br />

Island. The historical earthquakes recorded in this zone indicate that the Cyprus<br />

fault is active.<br />

The lines in figure 1.20B represent the major faults in the region. According to the<br />

seismotectonic maps of Jordan, the earthquake epicenters are well located along faults<br />

number 1, 2, 5, 8, 9, 10 and 11, while there is random distribution of the earthquakes<br />

epicenters in the proximity of the remaining faults (3, 4, 6, 7, and 12) (Al-Tarazi 1992).<br />

Figure (1.21): The Dead Sea fault and the adjacent branching faults, 1900-1980<br />

(Modified from Brew 2001, figure 4.9, e).<br />

1.4.3.3. Seismic maps of the JDTZ<br />

The Jordan Seismological Observatory began operation to collect and document<br />

seismic data in September 1983. The earthquakes were recorded in digital mode and<br />

processed at the Natural Resources Authority in Amman. All seismic data include the<br />

origin times, magnitude, epicenters in geographic locations (degrees and minutes), and<br />

37


focal depths (hypocenters) in kilometers (JSO 2005). After more than twenty years<br />

(1983-2005) of continuous operation of the seismic network in the region, more than<br />

10,000 earthquakes were recorded in Jordan, mostly distributed along the Jordan-Dead<br />

Sea Transform Zone where most of the mapped active fault zones in the region are<br />

(Olimat 2001) (figure 1.201). An earthquake catalog of the Middle East countries was<br />

compiled from seismic events between 1900 and 1983. This catalog was used to create a<br />

seismic map of the Middle East including the Arab countries located in northern Africa<br />

(Riad and Meyers 1985, Riad et al. 1985). Figure 1.22 is a modified map from Riad and<br />

Meyers (1985) that shows the seismic events in Jordan and surrounding countries during<br />

that period of time.<br />

Figure 1.22: Seismic map of the Middle East 1900 – 1983 (Modified from Riad and<br />

Meyers 1985).<br />

38


A new computerized regional tectonic map of Jordan and the neighboring<br />

countries was produced, which shows the main regional structures in Jordan and the<br />

surrounding area. The purpose of this map is to illustrate the seismic networks that exist<br />

in Jordan and surrounding countries and to show the relationship between earthquakes<br />

and active faults in the JDTZ. The maps shown in figure 1.20 were georeferenced in<br />

ArcGIS. The active fault lines and seismic zones were then digitized to create layers for<br />

more accurate manipulation that could be presented on a seismic map (figure 1.23). In<br />

addition, using the provided earthquake data, two maps were generated of Jordan and the<br />

surrounding countries that show the distribution of earthquake epicenters and their local<br />

Richter magnitudes.<br />

All earthquakes were recorded in local magnitude (M L ) scale which is basically<br />

the Richter magnitude scale that quantifies the amount of seismic energy released by an<br />

earthquake (Richter 1935). Earthquakes of local magnitude of four and greater (M L ≥ 4)<br />

only were mapped. These types of events are noticeable and could cause shaking of<br />

indoor items, rattling noises, and some damage, but no major destruction (Richter 1935).<br />

The major earthquakes maps are presented to illustrate the magnitudes of the seismic<br />

events over time based on the method of collecting the data (figures 1.24 and 1.25) where<br />

all seismic events are represented using circle proportional symbols (Dent 1999).<br />

Historical earthquake data as well as data from 19A.D. to August 1983 were<br />

compiled from multiple published references that studied and recorded the seismicity of<br />

the Middle East including Jordan. The magnitudes of these seismic events were translated<br />

from the Mercalli Intensity Scale, which is based on the observed historic structural<br />

destruction, to the approximate Richter Scale magnitudes (JSO, Personal<br />

39


communication). Some of the previous earthquake catalogues and sources are:<br />

Ambraseys (1978), Amiran (1951, 1952), Ben-Menahem (1991), Gutenberg and Richter<br />

(1956), Karnik (1969), Poirier and Taher (1980), Riad and Meyers (1985), the Bulletin of<br />

the International Seismological Centre (ISC), the Bulletin of Preliminary Determination<br />

of Epicenters (PDE), and the National Earthquake Information Service (NEIS) Bulletin<br />

provided by United States Geological Survey (USGS).<br />

Earthquake data from September 1983 to 2005 were mostly recorded by the<br />

Jordan Seismological Observatory (JSO) stationed at the Natural Resources Authority<br />

(NRA) in Amman, Jordan. Data were delivered in a simple text format (*.txt) with<br />

information such as date of activity (day, month, year), time of occurrence, latitude, and<br />

longitude of earthquake events and their local magnitudes and depth in kilometers (JSO,<br />

Personal communication).<br />

In addition, contemporary earthquakes events of the Middle East region, in Jordan<br />

in particular can be obtained from Jordan Seismological Observatory (JSO), the United<br />

States Geological Survey (USGS), the British Geological Survey (BGS), Israel<br />

Geological Survey (IGS), the Helwan Observatory, Cairo, Egypt (Degg 1990), and the<br />

Institute of Petroleum Research and Geophysics (IPRG) bulletin in Holon (Al-Tarazi<br />

1992).<br />

40


Figure 1.23: Seismic zones and active faults of Jordan and surrounding countries.<br />

41


1.4.3.4. Jordan/JDTZ earthquakes data<br />

Earthquake data presented in the seismic maps of Jordan and within the JDTZ are<br />

as accurate as their source material. Earthquake data included in the tectonic maps covers<br />

Jordan and its vicinity that lie between longitude 32.00°-39.00° east and latitude 27.00°-<br />

35.50° north (all coordinates are in decimal degrees). Magnitude measures the strength of<br />

an earthquake as recorded by a seismometer (Richter 1935). In order to keep all map<br />

earthquake data consistent, local magnitude (M L ) values were used due to their<br />

availability in all seismic data sets. The local magnitudes (M L ) are given for every<br />

recorded seismic event, while intensity values, if available, are in modified Mercalli<br />

intensity scale. The accuracy in the focal depth is proportional to the date and size (i.e.<br />

magnitude) of the recorded earthquakes. In case no determination is possible, depths were<br />

recorded as 0km. The accuracy of the epicentral location is classified according to the<br />

date as follows:<br />

1) 1A.D.-1899: For this period, which includes the historical earthquakes, the<br />

accuracy is expected to range between 50 and 150km.<br />

2) 1900-1980: ±10 km for events lying in between longitude 35.00°-36.00°E and<br />

29.50°-33.00°N, (longitude 53°03’60”E and latitude 29°53’30”N), while for the other<br />

events ±15-25 km.<br />

3) 1981-2005: ±5 km for events between longitude 35.00°-36.00°E and 29.50°-<br />

33.00°N, (longitude 53°03’60”E and latitude 29°53’30”N), while for the other events<br />

±10-15 km.<br />

All earthquake raw data were converted from their formats into Microsoft Office<br />

Excel format (*.xls). Redundant and missing values were eliminated. After that, data<br />

42


were converted into database (dBase IV) format (*.dbf) to be readable by the Geographic<br />

Information System software (i.e. ArcGIS). The earthquake data were imported into<br />

ArcGIS using “Add XY Data” under the “Tools” function where the X axes were<br />

assigned the longitude values and the Y axes assigned the latitude values. Finally,<br />

shapefiles were created for each set of the seismic data (data were assigned the same<br />

coordinate system as the geographic layers of the study area) and recorded on the seismic<br />

maps of Jordan.<br />

All seismic data are projected to the European Datum of 1950 Zone 36 North, the<br />

mean datum for Jordan and Israel, as shown in figures 1.24 and 1.25. All vector data are<br />

projected to the World Geodetic System (WGS) of 1984 ellipsoid and datum, Zone 36<br />

North, under the Universal Transverse Mercator (UTM) coordinate system.<br />

43


Figure 1.24: Major earthquake events on Jordan, 19 A.D. – August 1983.<br />

44


Figure 1.25: Major earthquake events on Jordan, September 1983 – 2005.<br />

45


2. Chapter Two: Literature Review<br />

2.1. Introduction<br />

2.1.1. Morphometric analysis in geomorphology<br />

Mountain fronts, valleys, and alluvial fans are surface features that construct the<br />

arid to semiarid landscape and exist at large or small scales. To understand the way<br />

landforms evolve, it is essential to study the underlying geology. In general, landform<br />

development implies deep structures of the earth; therefore there is always a strong<br />

relationship between landscape and the geologic environment (Keller and Pinter 2002). In<br />

recent years, the advancements in computer technologies and digital data<br />

acquisition/processing has led to the improvement of the knowledge of geomorphic<br />

processes and the development of the use of predictive models and quantitative<br />

measurements to analyze, monitor, and understand landform changes (Summerfield 1997,<br />

Wood 1996). This advancement has allowed geographers, geologists, and<br />

geomorphologists to explore human/land interaction utilizing modeling and systems<br />

analysis in their geomorphological studies that relied on sophisticated hardware and<br />

software tools (Baker 1986a).<br />

The study of the nature of landforms, landscapes, and surface processes including<br />

their description, classification, origin, development, and history highlighting the<br />

physical, biological, and chemical aspects is known as geomorphology, which may have<br />

either a qualitative or quantitative representation (Baker 1986a, Easterbrook 1999, Keller<br />

and Pinter 2002, Morisawa 1985). According to Morisawa (1985), quantitative<br />

geomorphology represents a new subfield of geomorphology that is defined as “the<br />

application of mathematics and statistical techniques to the study of landforms, their<br />

46


description and the processes by which they are created and changed”. Hence, the<br />

quantitative measurement and analysis of landforms and topography are the fundamental<br />

factors of morphometry (Hayden 1986, Keller and Pinter 2002) or geomorphometry<br />

(Summerfield 1997) that summarize numerical definitions of the Earth’s surface shape in<br />

correlation with landscape processes. Morphometric analyses in tectonic geomorphology<br />

studies basically refer to the measurement on topographic maps (recently DEMs) of<br />

quantitative parameters (Wells et al. 1988).<br />

Geomorphology is a significant tool in tectonic studies when using the<br />

geomorphic record. Such record includes several landforms and the Quaternary deposits<br />

that capture immense amount of information from the last few thousands and extend to<br />

about two million years (Keller and Pinter 2002). Tectonic geomorphology focuses on<br />

the contrast between topography and geomorphic features generated by tectonic<br />

processes and the erosion factors caused by surface processes that tend to wear them<br />

down. Defining the relationship between theses processes and interpreting the resulting<br />

landscape features is the main focus of tectonic geomorphology (Baker 1986a, Bull 1984,<br />

Burbank and Anderson 2001).<br />

Major progress in the field of tectonic geomorphology has been made during the<br />

last three decades, primarily due to the increased potential of evaluating the time factor in<br />

landscape development (Bull 1984). Therefore, through the use of computerized models<br />

of landform change, it is possible to determine the magnitude and frequency of<br />

displacements along faults and allocating classes of relative tectonic activity (Baker<br />

1986a). Consequently, tectonic geomorphology might be defined into two categories: (1)<br />

the study of landforms formed by tectonic processes; focusing on the shapes and origins<br />

47


of landforms as a result of tectonic activities, or (2) the application of geomorphic<br />

principles to explain tectonic problems; analyzing landforms to evaluate the history,<br />

magnitude, and rate of tectonic processes (Keller and Pinter 2002). The current research<br />

mainly deals with the second definition of tectonic geomorphology that involves using<br />

geomorphological indices to analyze existing landforms, namely mountain fronts and<br />

their associated valleys, in an effort to determine their tectonic activity classes.<br />

2.1.2. Remote sensing and GIS uses in geomorphology<br />

Earth-observing satellites, airborne sensor systems and aerial and space<br />

photography have nearly complete coverage of the Earth’s surface that provides images<br />

of different formats and various scales. This permits not only interpretation of landscape<br />

evolution, but rather offers the opportunity to integrate observation of a variety of<br />

processes over a large region. Geomorphic analysis from space has the advantage of<br />

allowing the use of quantitative methods for both data gathering and information<br />

extraction. Thus, satellite images are becoming useful and necessary in geomorphology,<br />

especially in obtaining quantitative measurements and performing geomorphic analyses<br />

(Hayden et al. 1986, Ulrich et al. 2003).<br />

Geographic Information Systems (GIS) have enhanced the applicability of<br />

geologic mapping when integrated with data obtained by remote sensing using a wide<br />

range of formats and scales. In addition, advancement in image analysis provides<br />

geologists opportunity to enhance, manipulate, and combine digital remotely-sensed data<br />

with several types of geographic information that in turn increases the amount of<br />

extracted information related to topographic and geologic features (Horsby and Harris<br />

48


1992). Satellite imagery permits research at different scales, which is valuable in the<br />

investigation of lineaments and faults (Arlegui and Soriano 1998).<br />

Digital enhancement of satellite images yields much information about image<br />

features. GIS techniques enable the integration and analysis of multi spatial and nonspatial<br />

data that have the same georeferencing scheme. Therefore, the integration of GIS<br />

and remotely sensed data could be more informative and results would be more<br />

applicable to image interpretation (Ehler 1992, Horsby and Harris 1992, Saraf and<br />

Choudhury 1998). Within the context of GIS, surface geomorphology is most commonly<br />

represented in Digital Elevation Models (DEMs) especially when quantitative<br />

measurement using geomorphometry is necessary. DEMs are generally defined as a<br />

regular two dimensional array of heights sampled above some datum that describes a<br />

surface (Wood 1996).<br />

On remotely sensed images, faults and edge segments (i.e. lineaments) are<br />

generally formed by an assortment of landscape elements that represent rock features on<br />

the land surface. Virtually all lineaments are discontinuous but due to the narrowly<br />

spaced edge and line segments, the human eye tends to merge them together to make<br />

them look continuous (Moore and Waltz 1983). Analyzing faults using remote sensing<br />

data is essential to fields such as tectonics, engineering geology, and geomorphology<br />

especially as they relate to tectonic analysis and earthquake hazards<br />

assessment/mitigation (Süzen and Toprak 1998).<br />

Tectonism in general has a geomorphic expression in the region where it occurs<br />

and its adjacent areas (Gerson et al. 1984). Any subsurface features such as faults,<br />

fracture zones, geological contacts, and numerous bedrock discontinuities have a<br />

49


significant surface expressions that can be detected by extensive analysis of digital<br />

satellite images and photographs that show linear or curvilinear topographic depression<br />

(Hardcastle 1995).<br />

The geomorphology of mountain fronts reveals much information regarding the<br />

tectonic activity occurring along them as well as their past history. Typically, earthquakes<br />

are concentrated on detached mountain fronts (Keller and Pinter 2002). In addition,<br />

alluvial fans are conical landforms characteristic of arid to semiarid regions and are<br />

associated with mountain fronts. They also commonly reveal insights into recent tectonic<br />

activity (Bull 1968, 1977a, Bull and McFadden 1977). Sediments eroded from the<br />

mountain are trapped at the mountain front to shape an endpoint of an erosionaldepositional<br />

system that forms a fan-shaped body. The connecting link between the<br />

depositional and erosional system is the stream. Many features contribute to the<br />

morphology of an alluvial fan, including the size of the drainage basin supplying<br />

sediments to the fan, source area geology, source area relief, vegetation, climate, and<br />

tectonic activity (Bull 1968, 1977a, Bull and McFadden 1977, Keller and Pinter 2002).<br />

2.2. Morphometric analysis approach<br />

Calculation of geomorphologic indices has been applied at different places around<br />

the world. However, there have been no serious attempts to employ this technique in a<br />

digital format rather than applying the broadly used conventional methods of William B.<br />

Bull (Bull 1968, 1977a). While this method of landform analysis has proven to be very<br />

valuable in tectonic investigations, no studies have been found that were carried out in<br />

the Middle East to examine its usefulness using either conventional or digital methods.<br />

50


The study of landforms and deposits developed or modified by tectonic processes<br />

can provide relevant information about the activity of the related tectonic structure. The<br />

geomorphic analysis of mountain fronts, related drainage network, and alluvial fan<br />

systems, provides valuable insights about the recorded tectonic history of any given<br />

region. Therefore, such studies at a regional scale have been frequently undertaken using<br />

morphometric analysis to calculate tectonic geomorphic indices. The most common<br />

indices are mountain front sinuosity (S mf ) and valley floor width to height ratio (V f ) that<br />

when combined together allow individual mountain fronts to be assigned to different<br />

tectonic activity classes (Bull 1968, 1977a, 1978, Bull and McFadden 1977, Silva et al.<br />

2003).<br />

In this approach, the measurements are normally calculated manually from<br />

topographic maps and/or aerial photographs. The elevation measurements for the valley<br />

height are obtained by using topographic maps. In general, these measurements are<br />

compared to measurements obtained in the field to determine their accuracy and<br />

consistency (Bull 1968, 1977a, 1978, Bull and McFadden 1977).<br />

2.3. Geomorphic indices of active tectonics<br />

Geomorphic indices were developed to acquire tectonic information about active<br />

tectonics in areas experiencing rapid deformation and to quantify the description of<br />

landscape (Bull 1977b, Bull and McFadden 1977, Keller and Pinter 2002, Zovoili et al.<br />

2004). In tectonic studies, geomorphic indices are valuable because the needed data can<br />

be easily attained from topographic maps and aerial photographs, plus they can be<br />

employed for evaluation of large areas. The results of the indices of an area might be<br />

51


combined together, or along with other information such as uplift rates to construct its<br />

tectonic activity classes (Bull 1977b, Keller and Pinter 2002).<br />

Below is a brief description of the most common geomorphic indices used in<br />

active tectonic studies. The description includes the index definition/explanation,<br />

mathematical formula, and tectonic geomorphological application.<br />

2.3.1. The Hypsometric Curve and Hypsometric Integral (H i )<br />

The hypsometric curve portrays the distribution of elevation across an area of<br />

land. One advantage of the hypsometric curve is that drainage basins of different sizes<br />

can be compared with each other as a function of elevation and area based on total<br />

elevation and total area plotted under the curve. This makes the hypsometric curve totally<br />

independent of differences in basin size and relief. Thus, the hypsometric curve scale<br />

could range from a single drainage to continents and even to the entire globe (Keller and<br />

Pinter 2002, Strahler 1952).<br />

The hypsometric curve is generated by plotting the relative drainage basin height<br />

(h/H) that is known as the total basin height ratio against the relative drainage basin area<br />

(a/A) which is the total basin area ratio (Keller and Pinter 2002, Strahler 1952). The<br />

maximum height (H) equals the maximum elevation minus the minimum elevation and<br />

represents the relief within the basin. The areas in between each pair of adjoining contour<br />

lines symbolize the total surface area of the basin (A). The area (a) is the surface area<br />

within the basin above a certain line of elevation (h). The relative area (a/A) value<br />

measures between 1.0 at the lowest point in the basin where relative height (h/H) equals<br />

zero, and zero at the highest point in the basin where relative height (h/H) equals 1.0<br />

(Keller and Pinter 2002, Mayer 1990, Strahler 1952), as illustrated in figure 2.1.<br />

52


Determining the hypsometric integral (H i ) is the simplest way to characterize the<br />

shape of the hypsometric curve for a given drainage basin. It is simply defined as the area<br />

under the hypsometric curve and calculated as follow:<br />

H =<br />

i<br />

mean elevation - minimum elevation<br />

maximum elevation - minimum elevation<br />

Calculating the hypsometric integral (H i ) is achieve by deriving the maximum and<br />

minimum elevation directly from a topographic map. The mean elevation is calculated by<br />

obtaining the mean of at least 50 elevation values in the basin using point sampling on a<br />

grid (Keller and Pinter 2002, Pike and Wilson 1971). It can also be evaluated directly<br />

from the digital elevation model (DEM) of the basin (Keller and Pinter 2002, Luo 2002,<br />

Luo and Howard 2005, Pike and Wilson 1971). The hypsometric integral and its<br />

relationship to the degree of dissection allows it to be used as an indicator of a<br />

landscape’s stage in the cycle of erosion. The theoretical evolution of the stage of a<br />

landscape is: (1) youthful stage, characterized by deep incision and rugged relief, (2)<br />

mature stage, where various geomorphic processes operate in near equilibrium, and (3)<br />

old stage, distinguished by a landscape near base level with very subdued relief. High<br />

hypsometric integral values indicate that most of the topography is high relative to the<br />

mean representing a youthful topography stage. Intermediate to low hypsometric integral<br />

values represent more evenly dissected drainage basins, indicating a mature stage of<br />

development (Keller and Pinter 2002, Mayer 1990, Strahler 1952).<br />

53


Figure 2.1: Hypsometric curve derivation from drainage basin (From Keller and Pinter<br />

2002, figure 4.1, p. 122).<br />

2.3.2. Drainage Basin Asymmetry (AF)<br />

Active tectonic deformation has its effect on the development of adjacent<br />

drainage basins. Such stream networks have distinctive patterns and geometries that can<br />

be described both qualitatively and quantitatively (Hare and Gardner 1985, Keller and<br />

Pinter 2002). Studying drainage systems provides information on the long-term evolution<br />

of the landscape (Burbank and Anderson 2001).<br />

The asymmetry factor (AF) was developed to detect tectonic tilting transverse to<br />

flow at drainage-basin or larger scales (Hare and Gardner 1985, Keller and Pinter 2002).<br />

The asymmetry factor is determined by the formula:<br />

AF = 100 (A r / A t )<br />

where A r is the area of the basin to the right of the trunk stream that is facing downstream<br />

and A t is the total area of the drainage basin. The asymmetry factor (AF) for most stream<br />

54


networks that formed and maintained flow in steady settings is 50. Since the asymmetry<br />

factor is susceptible to any tilting perpendicular at the trunk of the stream, any AF values<br />

greater or less than 50 indicate the possibility of tilting. Any drainage basin with a<br />

flowing trunk stream that was subjected to a tectonic rotation will most likely have an<br />

effect on the tributaries’ lengths. Assuming the tectonic activity caused a left dipping to<br />

the drainage basin, the tributaries to the left of the main stream will be shorter compared<br />

to the ones to the right side of the stream with an asymmetry factor greater than 50, and<br />

vice versa (Hare and Gardner 1985, Keller and Pinter 2002), as shown in figure 2.2.<br />

Figure 2.2: Block diagram shows the effect of an asymmetry factor with a left side tilt on<br />

tributaries lengths (From Keller and Pinter 2002, figure 4.3, p. 125).<br />

Another quantitative index to evaluate basin asymmetry is the Transverse<br />

Topographic Symmetry Factor (T) that is defined as:<br />

T = D a / D d<br />

where D a represents the distance from the midline of the drainage basin to the midline of<br />

the active meander belt, and D d corresponds to the distance from the basin midline to the<br />

basin divide (figure 2.3). For diverse segments of valleys, the calculated T values indicate<br />

55


migration of streams perpendicular to the drainage-basin axis. Thus, the Transverse<br />

Topographic Symmetry Factor is a vector that has direction and magnitude that ranges<br />

from zero to one (T = 0 to 1), which reflects a perfect asymmetric basin or a tilted one<br />

respectively (Burbank and Anderson 2001, Cox 1994, Cox et al. 2001, Keller and Pinter<br />

2002). In case of a negligible influence by the bedrock tilting on the relocation of the<br />

stream channels, the direction of the regional migration is an indicator of the ground<br />

tilting in that similar direction. The analysis of numerous drainage basins in an area<br />

results in multiple spatially distributed T vectors, which, when averaged, define the<br />

irregular zones of basin asymmetry. The calculation of both AF and T is a quantitatively<br />

rapid method of identifying ground tilting (Cox 1994, Cox et al. 2001, Keller and Pinter<br />

2002).<br />

Figure 2.3: An example of calculating a drainage-basin transverse topographic<br />

asymmetry vector for a single stream segment (From Cox 1994, figure 3, p. 574).<br />

56


2.3.3. Stream Length-Gradient Index (SL)<br />

The Stream Length-Gradient Index (SL) is calculated along a river and used to<br />

evaluate the erosional resistance of the available rocks and relative intensity of active<br />

tectonics. The SL index has sensitivity to channel slope changes, which makes it a good<br />

evaluation tool for the relationship between potential tectonic activity, rock resistance,<br />

topography, and length of the stream (Azor et al. 2002, Hack 1973, Keller and Pinter<br />

2002, Zovoili et al. 2004), as illustrated in figure 2.4.<br />

Figure 2.4: Map showing the Stream Length-Gradient Index (SL) for the South<br />

Mountain-Oak Ridge, Ventura basin in south California (From Azor et al. 2002, figure 8,<br />

p. 750).<br />

57


The Stream Length-Gradient Index (SL) is calculated using the following<br />

formula:<br />

SL = (∆H / ∆L) L<br />

where SL is the Stream Length-Gradient Index, L is the total channel length from the<br />

midpoint of the reach -where the index is calculated- upstream to the highest point on the<br />

channel, and ∆H/∆L is the channel slope or gradient of the reach, where ∆H represents<br />

the change in elevation for a particular channel of the reach with respect to ∆L that<br />

symbolizes the length of the reach. The calculation of the SL index is typically achieved<br />

by obtaining the needed parameters that are directly measured from topographic maps<br />

(Azor et al. 2002, Hack 1973, Keller and Pinter 2002).<br />

The SL index is associated with stream power, which is a product of unit weight<br />

of water, discharge, and energy slope. Total stream power available at a particular reach<br />

of a channel is correlated to the ability of a stream to erode its bed and transport<br />

sediments. Hence, the total stream power is a significant hydrologic variable that is<br />

proportional to the slope of water surface and discharge. In addition, discharge generally<br />

correlates with upstream channel length and the energy slope is estimated by the slope of<br />

the channel bed, which is essential for forming and preserving rivers (figure 2.5). In<br />

landscape evolution, it is assumed that stream profiles adjust quite rapidly to rock<br />

resistance. Therefore, the SL index is applied to identify recent tectonic activity by<br />

recognizing high index values variations on a particular rock type. For this purpose, the<br />

SL index is generally calculated for a number of reaches along major streams that erode<br />

the area and results merged for analysis. Commonly, high SL index values are present<br />

where rivers cross hard rocks and reflect relatively high tectonic activity, while low SL<br />

58


index values indicate relatively low tectonic activity and suggest less-resistant and softer<br />

rock types (Hack 1973, Keller and Pinter 2002).<br />

Figure 2.5: Diagram shows the process of calculating the Stream Length-Gradient Index<br />

(SL) for a given creek (From Keller and Pinter 2002, figure, 4.6, p. 128).<br />

2.3.4. Triangular Facets Index (Pf)<br />

The topography of the mountain fronts is affected by factors such as the relative<br />

rates of faulting, erosion and deposition that determine its evolution. Rivers that flow<br />

from uplifted footwall across faults have the tendency to dissect and divide mountain<br />

fronts; on the other hand, active faulting tends to reshape their linear characters. For<br />

example, simple block uplift with the existence of two sloping sides bordered with faults<br />

will produce regularly spaced, similarly sized, and shaped basins on each side that are<br />

characterized by valleys with wide basins and narrow throats -referred to as “wine glass”-<br />

59


as they pass across the active range front. In addition, such uplift will also create a linear<br />

rang front, large triangular facets, and small piedmont fans. Therefore, the spacing of<br />

facets along range fronts reveals the evolution of drainage basins within the footwall<br />

block (Burbank and Anderson 2001, Mayer 1986), as shown in figure 2.6.<br />

Figure 2.6: (A) Rapid block uplift produces linear range front, large facets, and small<br />

fans. (B) Slow deformation cause by uplift produces irregular range front, dissected<br />

facets, and large fans (From Burbank and Anderson 2001, figure 10.1, p. 202).<br />

The actual spacing of the basins relies on their shape being circular or elongated.<br />

The spacing can be measured as the ratio (i.e. index) between the basins mean length -<br />

which is the mean distance from the main drainage divide to the mountain front- to the<br />

mean spacing of the mouths of the basins along the range front. Thus, circular basins will<br />

create broader triangular facets, while more elongated basins will produce smaller and<br />

60


more closely spaced facets (Burbank and Anderson 2001, Mayer 1986, 1990), as shown<br />

in figure 2.7. Tectonically active fault blocks will usually have higher index values that<br />

are characterized by shorter facets, elongated basins with short drainages and more<br />

closely spaced rivers. Less active tectonic fault blocks which usually are associated with<br />

older mountains, on the other hand, are distinguished by longer facets, circular basins and<br />

irregular widely-spaced rivers that show low index values. Hence, the Triangular Facets<br />

Index (Pf) is a good indicator of tectonic activity (Burbank and Anderson 2001).<br />

Figure 2.7: Circular and elongated basins (From Burbank and Anderson 2001, figure<br />

10.2, p. 203).<br />

Triangular facets are interpreted as variably degraded remnants of fault-generated<br />

footwall scarps where the degraded scarp defines the height of the facet, and the spacing<br />

of drainages incised into the footwall defines the facet width (Wallace 1978). Usually, the<br />

apex of the triangular facet is the crest of the divide between dissected drainage basins<br />

and the base corresponds to the faulted mountain front (Yeats 1997). Accordingly, the<br />

older triangular facets (i.e. first generation facets) are located away from the active<br />

mountain front, whereas the younger facets (i.e. second generation facets) are positioned<br />

more closely to the active mountain fronts (Zovoili et al. 2004), as illustrated is figure<br />

2.8.<br />

61


Figure 2.8: Location of older and younger triangular facets to mountain fronts (Modified<br />

from Zovoili et al. 2004, figure 6, p. 1720).<br />

2.3.5. Mountain front sinuosity (S mf )<br />

Mountain Front Sinuosity, a widely used geomorphic measure of seismic activity,<br />

simply reflects the balance between the tendency of uplift to maintain a fairly straight<br />

front and erosion caused by streams that tend to generate irregularities in the front over<br />

time creating a sinuous topographic structure. The degree of erosional modification of<br />

tectonic structures is measured by the mountain front sinuosity index (Bull 1977a, 1978,<br />

Bull and McFadden 1977, Keller and Pinter 2002, Rockwell et al. 1984, Silva et al. 2003,<br />

Wells et al. 1988). Mountain front sinuosity (S mf ) is defined as the ratio between (L mf ) the<br />

length of the mountain front along its base at the distinct break in slope and (L s ) the<br />

straight line length of the whole mountain front (Bull 1977b, 1978, Bull and McFadden<br />

1977, Keller and Pinter 2002) and is expressed in the formula:<br />

S mf = L mf / L s<br />

where S mf is the mountain front sinuosity index, L mf is the length along the edge of the<br />

mountain-piedmont junction, and L s is the overall length of the mountain front.<br />

62


Typically, lower values of S mf indicate active uplift processes, while higher values signify<br />

relatively less tectonic activity (Bull 1977b, 1978, Bull and McFadden 1977, Burbank<br />

and Anderson 2001, Keller and Pinter 2002, Wells et al. 1988) (figures 2.9 and 2.10).<br />

Figure 2.9: Calculating mountain front sinuosity (S mf ) index (Modified from Keller and<br />

Pinter 2002, figure 4.14, p. 137).<br />

Figure 2.10: Mountain front sinuosity (S mf ) index (Modified from Burbank and Anderson<br />

2001, figure 10.5, p. 205).<br />

63


The sinuosity (S mf ) values can be calculated from topographic maps or aerial<br />

photographs. Because S mf values are scale dependent, it is more useful to calculate them<br />

using larger scales that accentuate the irregularity of the mountain fronts. Lower values of<br />

S mf index indicate relatively active mountain fronts, while higher values signify a<br />

relatively moderate to less active (inactive) mountain fronts (Bull 1977b, 1978, Bull and<br />

McFadden 1977, Burbank and Anderson 2001, Keller and Pinter 2002).<br />

2.3.5.1. Choosing mountain fronts<br />

Both L mf and L s are measured manually in the same units as the topographic map<br />

scale (e.g. meters, feet, etc.) then fed into the equation to obtain results, thus the S mf index<br />

is unitless (Bull 1977a, 1978, 1984, Bull and McFadden 1977, Keller and Pinter 2002,<br />

Rockwell et al. 1984, Silva et al. 2003, Wells et al. 1988).<br />

Mountain fronts are defined as major fault-bounded topographic escarpments with<br />

measurable relief exceeding one contour interval of 20m (Wells et al. 1988). Mountain<br />

fronts can be calculated as one front divided into segments of approximately 1Km long<br />

(Azor et al. 2002) or as several continuous fronts of various lengths (Bull 1978, 1984,<br />

Silva et al. 2003, Wells et al. 1988). The latter approach has been adopted in this research<br />

since it is widely used and is more suitable to the current study area. According to Wells<br />

et al. (1988) and based on the method produced by Bull (1978, 1984), longer mountain<br />

fronts are subdivided into discrete segments with generally similar geologic and<br />

physiographic characteristics, based on one or more of the following criteria: (1)<br />

Intersection with cross-cutting drainages large in scale relative to the front, (2) Abrupt<br />

deflections in mountain front orientation, (3) Abrupt changes in lithology, and (4) Abrupt<br />

64


changes in the main geomorphic characteristics of a mountain front relative to adjacent<br />

front segments such as relief, steepness, or dissection (Wells et al. 1988).<br />

2.3.6. Valley floor width to valley height ratio (V f )<br />

The other important stability index is the ratio of valley floor width to valley<br />

height (V f ). This index reflects the differences between the V-shaped valleys downcutting<br />

in response to active uplift, where the stream is governed by the influence of a base level<br />

fall at some point downstream that indicates a relatively high tectonic activity, and the U-<br />

shaped broad-floored valleys with principally lateral erosion into the adjacent hillslopes<br />

in response to relative base-level stability or tectonic quiescence that signifies a relatively<br />

low tectonic activity. Therefore, this index uses one vertical and one horizontal<br />

dimension at a given point along the stream in the erosional system. The ratio of valley<br />

floor width to valley height is defined as:<br />

V<br />

f<br />

2V<br />

fw<br />

=<br />

[( E − E ) + ( E − E )]<br />

ld sc rd sc<br />

where V fw is the width of the valley floor, E sc is the elevation of the valley floor or stream<br />

channel, and E ld and E rd are the elevations of the left and right valley divides respectively,<br />

as shown in figures 2.11 and 2.12. Similar to the S mf index, lower values of the V f index<br />

indicate relatively active mountain fronts and reflect deep valleys with active incision<br />

related to uplift, whereas higher V f index values are associated with relatively moderate<br />

to less active mountain fronts that represent low uplift rates (Bull 1977a, 1978, Bull and<br />

McFadden 1977, Burbank and Anderson 2001, Keller and Pinter 2002, Rockwell et al.<br />

1984, Silva et al. 2003, Wells et al. 1988).<br />

65


Figure 2.11: Calculating valley floor width to height ratio (V f ) (From Keller and Pinter<br />

2002, figure 4.15, p. 139).<br />

Figure 2.12: Valley floor width to height ratio (V f ) (From Burbank and Anderson 2001,<br />

figure 10.6, p. 205).<br />

2.3.6.1. Choosing valley profiles<br />

Similar to the S mf index, all V f index measurements are usually obtained from<br />

topographic maps and aerial photographs (Bull 1977a, 1978, 1984, Bull and McFadden<br />

1977, Keller and Pinter 2002, Rockwell et al. 1984, Silva et al. 2003, Wells et al. 1988).<br />

The location of the cross-valley (i.e. valley profile) transects within a drainage basin<br />

affect the values of V f . Valley floors tend to become gradually narrower upstream from<br />

the mountain front and for a given stream the values of V f ratios tend to become<br />

increasingly larger downstream from the headwaters (Bull and McFadden 1977). In<br />

66


addition, the values of V f may also vary widely among streams with different drainage<br />

basin areas, discharge, and underlying bedrock lithology (Wells et al. 1988).<br />

Consequently, each study area will dictates its own valley profile measurement<br />

distance from a given mountain front based on its distinctive geomorphology and the<br />

geospatial distribution of valleys. The V f measurements were taken at a distance of about<br />

200m from mountain fronts (Zovoili et al. 2004), 250 m upstream from the mountain<br />

front (Silva et al. 2003), at a distance of 0.1 of the drainage basin length (Rockwell et al.<br />

1984), and approximately upstream at a distance of 1Km from the mountain front (Bull<br />

and McFadden 1977).<br />

Both S mf and V f values have been used to evaluate the relative degree of tectonic<br />

activity of related mountain fronts (Bull and McFadden 1977, Keller and Pinter 2002,<br />

Silva et al. 2003). However, it is very important to specify that only the combination<br />

between S mf and V f indices, especially in arid to semiarid regions are able to provide<br />

semi-quantitative information of the relative degree of tectonic activity of the examined<br />

mountain fronts and assigning them to different tectonic activity classes (Bull and<br />

McFadden 1977, Silva et al. 2003). Therefore, in this research both of these geomorphic<br />

indices were used.<br />

2.4. Satellite imagery and digital elevation models<br />

The main focus in this research is to calculate these two tectonic geomorphic<br />

indices, namely mountain front sinuosity and the valley floor width to valley height ratio,<br />

to indicate the relative seismic activity levels of the mountain fronts in JDTZ. The<br />

calculation of measurements requires elevation data that is obtainable using remote<br />

67


sensing imagery and digital elevation models (DEMs) of the study area as input layers<br />

which will be integrated using geographic information system (GIS).<br />

In previous studies conducted in different countries, the values of S mf and V f were<br />

calculated manually from topographic and geomorphological maps and aerial<br />

photographs of various scales (chapter 2, section 2.6). The best topographic maps of the<br />

JDTZ are at a scale of 1:50,000 with 20m contour intervals (figure 2.13). Producing<br />

DEMs from digitized topographic maps is time consuming and produces less-accurate<br />

results than digital topographic maps and satellite derived DEMs (Toutin and Cheng<br />

2001). Therefore, using available commercial DEMs data generated from satellite data is<br />

more convenient and has better resolution.<br />

2.4.1. Digital Elevation Models<br />

Digital elevation models offer the most common methods for extracting vital<br />

elevation and topographic information. DEMs are increasingly used for visual analysis of<br />

topography, landscapes and landforms, in addition to modeling of surface processes<br />

(Hirano et al 2003, Kamp et al. 2003, 2005, Welch 1990). Currently, DEMs have been<br />

the main source for the extraction of different geomorphological and topographic features<br />

depending on altitude and its spatial distribution and variation (Felicísimo 1994). Digital<br />

Elevation Model (DEM), Digital Elevation Data (DED), Digital Terrain Data (DTD)<br />

(Campbell 2002), or Digital Terrain Model (DTM) all include various arrangements of<br />

individual points of x (east-west direction) and y (north-south direction) coordinates of<br />

horizontal geographic locations. Z is the vertical elevation value that is relative to a given<br />

datum for a set of x, y points (Bernhardsen 1999, Bolstad and Stowe 1994, Welch 1990).<br />

They consist of samples array of elevations for a number of ground positions at equally-<br />

68


spaced intervals (USGS 1990). DEM provides a digital representation in threedimensions<br />

of a portion of Earth’s terrain. The resolution of DEMs depends on scale and<br />

resolution of the data source (digital satellite images, aerial photographs) and the spatial<br />

resolution (i.e. grid spacing) of the data samples, as well as other variables like data<br />

structure and algorithms used during the extraction process (Campbell 2002, Cuartero et<br />

al. 2004, Sabins 1997, USGS 1990).<br />

DEMs are most commonly prepared in raster data structure, which are compatible<br />

with remotely sensed data. They are represented in an array of equally spaced grids<br />

having values of the topographic elevation observed and recorded of the earth’s surface.<br />

It is similar to any remote sensing data except that each pixel shows an elevation<br />

measurement in the center of the pixel instead of brightness values (i.e. digital numbers<br />

or DNs). Using this format makes the process of manipulations, classification, analysis,<br />

and display of DEMs similar to that of remote sensing imagery (Campbell 2002). The<br />

form of surface model used for this entire study is that of the Digital Elevation Model<br />

(DEM). Although the term is used inconsistently in the literature (Burrough 1986, Weibel<br />

and Heller 1991) it is defined here consistently with the terms of Burrough (1986), as a<br />

regular gridded matrix representation of the continuous variation of relief over space<br />

(Wood 1996).<br />

69


Figure 2.13: The Aqaba 1:50,000-scale topographic map with 20m intervals. Produced by<br />

the Unites States Army, Sheet 3049 III, Series K737.<br />

70


In the last decade several developments have been introduced to satellite sensors<br />

to produce data for digital elevation model generation. Nowadays many satellites provide<br />

stereo images with high potential of producing DEMs that can be integrated in<br />

visualization software or GIS environments with available geodata and cartographic<br />

information (i.e. existing vector data) for landscape and geomorphic analysis (Poli et al.<br />

2005). However DEMs of usable details are still not available for much of the Earth, high<br />

accuracy determination and visualization of topography of the Earth’s surface is still very<br />

essential for local and national level environmental applications (Chrysoulakis et al.<br />

2004).<br />

The use of three-dimensional terrain modeling in GIS applications was made<br />

possible by the advancement in computer and database technology. The primary<br />

requirement for such application is using a DEM of the terrain within the region of<br />

interest. When combines with satellite images and GIS coverages, a DEM becomes more<br />

useful in terrain visualization and geomorphic terrain analyses (Welch 1990).<br />

The accuracy of DEMs depends on the level of detail of the source and the grid<br />

spacing used to sample the source. The scale of the source material is the main limiting<br />

factor for the level of detail of the source. DEMs are classified into three levels of quality<br />

that characterizes the model’s accuracy (USGS 1990, 1997-1998): (1) Level-1 DEMs are<br />

the standard format elevation datasets. They have the desired accuracy standards of 7m<br />

vertical root mean square error (RMSE) that doesn’t exceed the maximum 15m RMSE,<br />

(2) Level-2 DEMs are elevation datasets that have been processed and smoothed for<br />

consistency and edited to remove systematic errors. The maximum vertical RMSE is onehalf<br />

contour interval with no errors greater than one contour interval, and (3) Level-3<br />

71


DEMs are elevation datasets derived from digital line graph (DLG) data using selected<br />

elements from hypsographic and hydrologic data. The maximum vertical RMSE is onethird<br />

contour interval with no errors greater than two-third of the contour interval.<br />

2.5. Advanced Spaceborne Thermal Emission and Reflection Radiometer Satellite<br />

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is<br />

an advanced multispectral imaging satellite, boarded on Earth Observing System EOS-<br />

AM1 platform (platform altitude of 705km) that was launched on board NASA’s Terra<br />

spacecraft in December, 1999 and placed in orbit in February 2000. ASTER is an alongtrack<br />

imager with a circular, near polar orbit (to increase the ground coverage), low<br />

inclination satellites for long-term global observations of the land surface, biosphere,<br />

solid Earth, atmosphere, and oceans at an altitude of 705km. The orbit is sunsynchronous<br />

with an equatorial crossing at local solar time of 10:30am, returning to the<br />

same orbit every 16 days. It has two visible bands, seven IR bands, and five thermal IR<br />

bands. The spatial resolution varies with wavelengths, 15m in the visible and the nearinfrared<br />

(VNIR), 30m in the short wave infrared (SWIR), and 90m in the thermal infrared<br />

(TIR). It is also equipped with off-nadir backward-viewing sensor pointing feature that<br />

has the capability to produce stereo images and in turn generate a high resolution DEMs<br />

(Abrams et al. 2003, Abrams and Hook 1995, 2002, ASTER websites, Childs 2003,<br />

Fujisada 1994, 1998, Fujisada et al. 1998, 2001, Kamp et al. 2003, 2005, Lang et al.<br />

1996, Selby 2003, Tokunaga et al. 1996, Toutin 2001, Toutin and Cheng 2001,<br />

Yamaguchi et al. 1998).<br />

All ASTER bands are designed to collect data over a swath (i.e. ground resolution<br />

cell) of 60km x 60km that requires nine seconds for each scene, and approximately 60-<br />

72


seconds for a stereo pair (Fujisada 1994, Lang et al. 1996). However, the data coverage is<br />

restricted to about 650-scenes per day that are processed to Level-1A; of these, about 150<br />

are processed to Level-1B, working under a limited 8% duty cycle (i.e. 8 minutes/orbit)<br />

and priority data acquirement with a global coverage between 85ºN and 85ºS (Abrams et<br />

al. 2003, Abrams and Hook 1995, 2002, ASTER websites, Childs 2003, Fujisada 1994,<br />

1998, Fujisada et al. 1998, 2001, Lang et al. 1996, Lang and Welch 1999, Tokunaga et al.<br />

1996, Toutin 2001, Toutin and Cheng 2001, Yamaguchi et al. 1998), as shown in figure<br />

2.14.<br />

Figure 2.14: Flat map shows ASTER DEM global coverage of January 31, 2004.<br />

2.5.1. ASTER data types<br />

The ASTER instrument has two types of data levels, Lavel-1A and Level-1B data.<br />

Level-1A data is basically defined as reconstructed, unprocessed instrument data at full<br />

resolution. Consequently, the Level-1A data consist of the image data, the radiometric<br />

coefficients, the geometric coefficients, and other supplementary data without applying<br />

73


any of the coefficients to preserve the original data values. The L1A data is used as<br />

source data to generate DEM products because of the many useful instrument parameters<br />

and information that are incorporated inside them. In addition, due to the maintained<br />

ancillary data which include the spacecraft position or the geometric correction table that<br />

contains the latitudes and longitudes of the collected pixels, high quality DEM data<br />

products can be generated (Abrams et al. 2003, Abrams and Hook 2002, Fujisada 1998,<br />

Fujisada et al. 2001, Yamaguchi et al. 1998).<br />

Alternatively, Level-1B data have no ancillary data, instrument geometric<br />

parameters, and the spacecraft information. The L1B data are normally generated<br />

applying these coefficients for radiometric calibration and geometric resampling. The<br />

L1B data product is produces, by default, in the UTM projection, in swath orientation,<br />

and Cubic Convolution resampling. However, the georeferenced and georectified L1B<br />

data is still able to produce practical quality DEM products for ASTER individual scenes<br />

(Abrams et al. 2003, Abrams and Hook 2002, Fujisada 1998, Fujisada et al. 2001, Poli et<br />

al. 2005, Yamaguchi et al. 1998). The data structure of an ASTER L1B data product is<br />

illustrated in figure 2.15.<br />

2.6. Previous studies in morphometric analysis<br />

In this section, a number of studies utilizing geomorphological indices as a tool<br />

for tectonic investigation will be described. Starting with the early studies that introduced<br />

quantitative analysis to geomorphology and ending with the most recent.<br />

The earliest application of geomorphology to the assessment of tectonic stability<br />

began with Bull and McFadden (1977). In their research conducted at the north and south<br />

ends of the Garlock fault in the Mojave Desert in California, the researchers employed<br />

74


S mf and V f index analysis to determine the Quaternary tectonic activity of the area. Based<br />

on the sinuosity values the tectonic activity of the area was classified into three classes.<br />

The area north of the Garlock faults has relatively low values of S mf index, while the area<br />

north of the fault shows a relatively high S mf index values. A transitional area in the<br />

central part of the northern area nearby the Garlock fault shows relatively high values of<br />

S mf index. Tectonic indices were calculated using elevation data obtained directly from<br />

aerial photographs, 1:62,000 scale topographic maps, and 1:250,000 topographic and<br />

geologic maps (Bull and McFadden 1977).<br />

Figure 2.15: Data structure of ASTER Level-1B granule (From Abrams et al. 2003.<br />

figure 8, p. 22).<br />

75


This study concluded that active tectonic terrains (class 1) are characterized by<br />

unentrenched alluvial fans, elongated drainage basins with narrow valley floors and steep<br />

hillslopes even in soft rock types, S mf index values of 1.0 to 1.6, and V f index values of<br />

0.05 to 0.9. Moderate to slightly active tectonism terrains (class 2) are differentiated by<br />

entrenched alluvial fans, large drainage basins that are more circular than class 1 basins,<br />

steep hillslopes, valley floors that are wider than their floodplains, S mf index values<br />

ranges 1.4 to 3.0, and V f index values of 0.5 to 2.0. The tectonically inactive terrains<br />

(class 3) are distinguished by pedimented mountain fronts and embayments, steep<br />

hillslope only on hard rock types, few large integrated stream systems in the mountains,<br />

S mf index values of 1.8 to more than 5, and V f index values greater than 2 (Bull and<br />

McFadden 1977).<br />

In a similar study conducted by Bull (1978) at the south front of the San Gabriel<br />

Mountains in California, geomorphic indices were calculated using 1:24,000-scale<br />

topographic maps with contour intervals ranging from 10 to 40 feet. This study concluded<br />

similar results to the north and south of the Garlock fault research and mountain fronts<br />

were represent the three tectonic activity classes (Bull 1978).<br />

In a parallel study, the mountain fronts and alluvial fans of the Ventura area in<br />

California were analyzed using S mf and V f indices (Rockwell et al. 1984). Eight range<br />

fronts were defined in the study area based on geographic location, geomorphic<br />

expression, and presence of known active faults and folds. This study yields two tectonic<br />

activity groups; group (1) has very active fronts while group (2) is associated with less<br />

active tectonism. The very active tectonism fronts (groups 1) are associated with<br />

faults/folds that were uplifted and tilted basinward generating a relatively large alluvial<br />

76


fans for given basin areas. The Less active tectonism fronts (group 2), on the other hand,<br />

has relatively small alluvial fans that are more constrained in their depositional areas. The<br />

alluvial fans with larger fan areas are associated with mountain fronts having higher rated<br />

of tectonic activity (Rockwell et al. 1984).<br />

The relatively active fronts produced lower S mf and V f values in comparison with<br />

the less active fronts that show higher values of both S mf and V f . The V f index values<br />

varies from 0.43 to 1.91, while the tectonically active fronts S mf index values ranging<br />

1.01 to 2.72 indicating an active uplift in the study area. The geomorphic analysis results<br />

indicated that tectonically active fronts have low S mf range from 1.01 to 1.34 with an<br />

average of 1.14, while the less active fronts have sinuosities that range from 1.57 to 2.72<br />

with an average of 2.04. The study concluded that both S mf and V f indices are useful<br />

indicators of relatively tectonic activity in the Ventura area. All Indices were calculated<br />

from the United States Geological Survey 7.5-minute topographic map (1:24,000-scale)<br />

with 40 foot contour intervals (Rockwell et al. 1984).<br />

Another study conducted by Wells et al. (1988) using tectonic geomorphology<br />

indices as an indicator to relative tectonic activity in the Pacific coastal mountains and<br />

piedmonts of Costa Rica. The research utilized morphometric analyses of 100 mountain<br />

fronts and abundant river long-profiles along with field studies and radiometric dating<br />

over two study areas (regions I and II) located within the subduction zone between the<br />

Cocos and the Caribbean tectonic plates (Wells et al. 1988).<br />

The geomorphic analysis results of the two regions have shown differences in<br />

values based on the region. Region I, located to the northern coastal areas within the<br />

transitional plate boundary zone, where region II is located in the southern segment that<br />

77


indicates an occurrence of high degree of tectonic activity on-shore opposite to the<br />

subduction seismic ridge. The S mf index values of region I range from 1.0 to 3.1<br />

indicating relatively high sinuosity values of mountain fronts that are more sinuous and<br />

dissected. On the other hand, region II S mf index results range from 1.0 to 2.2 that signify<br />

relatively low sinuosity values of mountain fronts -compared to region I- that are less<br />

sinuous and dissected due to their location in the interior mountainous regions. In<br />

general, low mean values of mountain front sinuosity were clustered around 1.2 to 1.5 in<br />

the more tectonically active region I and its subregions, while the mean values were<br />

between 1.1 to 1.5 in the less active region II and its subregions. On the other hand, the<br />

V f index values ranging from 1.1 to 32, with typical values of 0.2 to 7. Individual stream<br />

in upstream regions (less active) show low V f values of less than 1 to 2. Where individual<br />

streams in downstream regions (more active) show higher V f ratios. The wide-floored<br />

valleys were located one or more kilometers from the escarpment and have high Vf<br />

values generally more than 2, where V-shaped valleys associated with development of<br />

deep and narrow canyons close or immediately upstream from the intersection with the<br />

fronts indicated low V f values generally less than 1. The entire geomorphic<br />

measurements were acquired from 1:50,000 scale topographic map with 20m contour<br />

intervals (Wells et al. 1988).<br />

This study emphasizes the practicality of geomorphic analysis for detecting<br />

spatial variation in plate tectonic framework within convergent tectonic plate boundaries<br />

(e.g. subduction ridges). Such morphometric analysis being normally utilized in arid and<br />

semiarid regions of compressional and extensional terrains along mountain fronts would<br />

yields satisfactory results when used in the coastal regions (Wells et al. 1988).<br />

78


In an attempt to provide information concerning the active fold growth in the<br />

South mountain-Oak Ridge, a tectonic geomorphic analysis study using several<br />

geomorphic indices was carried out by Azor et al. (2002). The South mountain-Oak<br />

Ridge near Ventura basin, southern California, is an asymmetric anticlinal uplift above<br />

the active and buried Oak Ridge reverse fault. The shortening along the fault started to<br />

accumulate since the Quaternary time and is responsible for the growth and current<br />

topography of the westernmost 15km of the ridge during the past 0.5Myr (Azor et al.<br />

2002).<br />

To quantify the geomorphology of the South Mountain-Oak Ridge, several<br />

geomorphic indices were involved in this research including stream length-gradient index<br />

(SL), mountain front sinuosity (S mf ), ratio of valley floor width to valley height (V f ), and<br />

hypsometric integral index (Hi). The S mf index values roughly decreased from<br />

approximately 2 to 1 along the northern slope of the anticlinal ridge towards the<br />

westernmost 10km of observed surface folding indicating a lower S mf values and active<br />

uplifting. In general, V f index values along the northern side of the ridge decreased<br />

westward from about 1.5 to 0.5 indicating rapid uplift and valley incision. Values of the<br />

Hi index along the northern side of the ridge increase considerably from roughly 0.35 to<br />

0.4 with a maximum of around 0.55. In addition, the northern, eroded fold scarp of the<br />

ridge represents were relatively high SL index values, which is a pattern consistent with<br />

the existence of active and rapid slip on the Oak Ridge fault. Evidently, the overall results<br />

obtained from geomorphic indices of the western segment of the South mountain-Oak<br />

Ridge emphasize the westward lateral growth of the underlying anticline. In conclusion,<br />

79


the tectonic geomorphic analysis of the ridge confirms the usefulness of geomorphic<br />

indices of active tectonics to identify and evaluate active fold growth (Azor et al. 2002).<br />

Recent research was conducted by Silva et al. (2003) to determine the tectonic<br />

activity over 17 different mountain fronts in southeastern Spain. The fronts are<br />

distributed along the Valencia Trough and the Eastern Betic Shear Zone (EBSZ), which<br />

are the two most prominent crustal-scale structures of the Mediterranean sector of Spain.<br />

Mountain front sinuosity values were calculated using 1:50,000-scale topographic and<br />

geomorphic maps with four contour intervals (100m height) produced by the authors of<br />

the study area, while the valley floor width/height ratio values were calculated from<br />

1:25,000-scale topographic maps (Silva et al. 2003).<br />

The geomorphic index values for the mountain fronts under study were classified<br />

into three tectonic classes and associated with an estimate of tectonic uplift rates. Class 1<br />

indicating tectonically active fronts with S mf index values ranging from 1.17 to 1.53<br />

(mean values = 1.4) and V f index values < 0.5. Class 2 indicating moderately active<br />

fronts with S mf index values ranging 1.8 to 2.30 and V f index values ranging 0.3 to 0.8.<br />

Finally, class 3 indicating inactive fronts with S mf values ranging 2.8 to 3.5 and V f index<br />

values that is > 0.7 and ranging 0.8 to 1.2 (Silva et al. 2003).<br />

After the application of S mf and V f analysis over the 17 mountain front in SE<br />

Spain, the study concluded the occurrence of different morphometric properties for<br />

different tectonic landscapes (i.e. tectonic classes) and faulting styles that could only be<br />

practically distinguished by means of statistical analysis using S mf /V f regression. These<br />

tectonic classes could be linked to the available uplift rates from the last 100kyr in both<br />

regions under study in SE Spain mountain fronts for better understanding of their tectonic<br />

80


activity. As a result, each tectonic activity class was assigned uplift rates and recurrence<br />

intervals of earthquake activities as follow, class 1 an uplift rate of > 0.15 to 0.08 m/kyr,<br />

class 2 an uplift rate of 0.07 to 0.03 m/kyr, and class 3 an uplift rate of < 0.03 m/kyr<br />

(Silva et al. 2003).<br />

Another recent study was undertaken by Zovoili et al. (2004) to study the tectonic<br />

geomorphology of escarpments of two faults located in mainland Greece. The<br />

Kompotades and the Nea Anchialos faults in the Sperchios and South Thessaly rift zones,<br />

respectively, were studied using morphometric analysis. Three geomorphic indices were<br />

applied namely mountain front sinuosity (S mf ), the valley floor width to valley height<br />

ration (V f ), and the stream length-gradient (SL) index (Zovoili et al. 2004).<br />

In order to gather more information about the tectonic activitie of the two faults,<br />

the historical seismicity of the region was taken into consideration. The V f index values<br />

ranged between 0.4 to 1.2, with more significant values close to 0.7, implying high uplift<br />

rates. While the S mf index values concentrated around ≈ 1 demonstrating relatively high<br />

tectonic activity in both faults that decreased toward the west. On the other hand, the SL<br />

index, which is more sensitive to non-tectonic processes such as rock resistance and<br />

stream length were found to be less indicative of tectonic activity (Zovoili et al. 2004).<br />

The recurrence interval of the Nea Anchialos fault according to the historical<br />

seismicity is about 1500 years and in case of the Kompotades fault the interval is more<br />

than 2500. Given that both faults have the same V f index values, this suggest that the Vf<br />

index seems to be sensitive for longer periods than 2500 years. This study concluded that<br />

the combined values of the S mf , V f , and SL indices calculations indicate that both faults<br />

81


are very active and they belong to the first class (i.e. class 1) of tectonic activity (Zovoili<br />

et al. 2004).<br />

Several studies in different places in the world have utilized tectonic geomorphic<br />

analysis approach to investigate tectonic activities in multiple geomorphic and geologic<br />

settings. For example, researches took place in the Gorajec river basin in Roztocze in SE<br />

Poland (Brzezińska-Wójcik et al. 2002), eastern California shear zone and parts of the<br />

basin and range located in eastern Mojave Desert (Dudash et al. 2003), southern<br />

interpolate Shillong Plateau in Bangladesh/India (Biswas and Grasemann 2005), the SW<br />

border of Sierra Nevada in Granada, Spain (El-Hamdouni et al. 2006), and the Alborz-<br />

Central Iran border zone, from the east of Varamin of the east of Semnan (Arian and<br />

Faranak 2006) all verified the usefulness of tectonic geomorphic index analyses in<br />

determining and classifying relative tectonic activity along mountain fronts and river<br />

basins.<br />

2.7. Summary<br />

Detailed quantitative measurements of landforms are able to provide essential<br />

information to objectively compare and calculate geomorphic indices that are practical<br />

for identifying the characteristics of a particular area such as its level of tectonic activity.<br />

Therefore, combined evaluation of several indices would seemingly develop a system of<br />

relative tectonic activity classes. Generally, the classification of areas being very active,<br />

moderately active, and less active (inactive) is useful in locating active structures and the<br />

calculation of active tectonic processes rates (Keller and Pinter 2002). A summary of the<br />

S mf and V f indices ranges of selected significant studies are listed in table (2.1).<br />

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Literature Tectonic Classes S mf ranges V f ranges<br />

1 1.0 - 1.6 0.05 - 0.9<br />

Bull & McFadden (1977)<br />

2 1.4 - 3.0 0.5 - 2.0<br />

3 1.8 - >5 >2.0<br />

Rockwell et al. (1984)<br />

Active fronts 1.01 – 1.34 (Ave. 1.14)<br />

Less active fronts 1.57 – 2.72 (Ave. 2.04)<br />

0.43 - 1.91<br />

Wells et al. (1988)<br />

More active 1.0 – 3.1 (mean 1.2 – 1.5) < 1.0, V- valley<br />

Less active 1.0 – 2.2 (mean 1.1 – 1.5) > 2.0, U- valley<br />

Azor et al. (2002) Active uplift Values Decreased ≈ 2 to 1 decreased ≈ 1.5 to 0.5<br />

1 1.17 – 1.53 (mean 1.4) < 0.5<br />

Silva et al. (2003)<br />

2 1.8 – 2.30 0.3 – 0.8<br />

3 2.8 – 3.5 > 0.7 (mostly 0.8 – 1.2)<br />

Zovoili et al. (2004) High upllifting Around 1.0 0.4 – 1.2 (significant 0.7)<br />

Table 2.1: The S mf and V f indices ranges of selected literature.<br />

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3. Chapter Three: Materials and Methods<br />

3.1. Introduction<br />

This chapter provides details of the methods and procedure used to collect the<br />

data for study. This includes the acquisition, preparation, and processing of the digital<br />

data, generating ASTER DEMs, and morphometric analyses. In addition, the digitizing of<br />

mountain front sinuosity and valley profiles over the areas that fit the geomorphic indices<br />

criterion applying the digital approach is explained. Finally, all analytical results are<br />

depicted in maps, three-dimensional images, and tables to ease the method of comparing<br />

results and extracting conclusions.<br />

3.2. The digital morphometric approach<br />

In general, all index measurements in the previous morphometric studies were<br />

manually obtained from topographic maps and aerial photographs of various scales where<br />

available. Therefore, the digital approach adopted in this study will try to replace<br />

topographic maps by digital elevation sources of the study area to calculate both S mf and<br />

V f indices. Toward this, digital elevation models (DEMs) and shaded relief maps of the<br />

study area replace topographic maps as elevation sources.<br />

Integrated layers of vector and raster data of both delineated mountain fronts and<br />

valley profiles that comprises digitized fronts and their overall lengths will operate as<br />

digital measurement tools. In addition, a three-dimensional cross section of each<br />

designated valley profile is used as an elevation reference for the right and left valley<br />

divides and its floor as well as a measurement tool to calculate each valley floor width.<br />

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3.2.1. Choosing mountain fronts<br />

In this current research, the mountain fronts were distinguished and delineated<br />

based on the presence of any intersection with large scale cross-cutting drainages.<br />

Generally, all selected mountain fronts were acknowledged as a single continuous front<br />

until they encountered major interruption by large-scale drainages or valleys. Hence, new<br />

mountain fronts start at another front that is discontinuous and/or trends in a different<br />

direction (Bull 1978).<br />

3.2.2. Choosing valley profiles<br />

In this study, the transect distance of valley profiles for determining V f values<br />

ranged between 45m to 1,200m (only two cases reached about 2,500m) upstream from<br />

the mountain fronts, and approximately parallel, for each given mountain front.<br />

Accordingly, a number of mountain fronts were associated with several valley profiles<br />

while other fronts were linked to at least one profile based on the ability of identifying<br />

pronounced valleys due to the DEM resolution and the availability of the digital data at<br />

the selected valley locations.<br />

3.3. ASTER Stereo capability<br />

The ASTER stereo subsystem that has the capabilities of generating DEMs<br />

include the nadir-looking and backward-looking telescopes that yields a base-to-height<br />

ratio (B/H) of 0.6 (Hirano et al. 2003, Lang et al. 1996, Tokunaga et al. 1996, Yamaguchi<br />

et al. 1998), which is close to ideal for generating DEMs with automated techniques for a<br />

variety of terrain conditions (Hirano et al. 2003). The visible/near-infrared (VNIR)<br />

subsystem has both nadir-looking (band 3N) and backward-looking telescopes (band 3B)<br />

pair in the near-infrared spectral band that is used for same orbit stereo imaging. The two<br />

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telescopes are designed to facilitate stereoscopic viewing capability in the along-track<br />

direction and to enable the large B/H ratio to be fixed at 0.6 (Fujisada 1998, Fujisada et<br />

al. 1998).<br />

One of the advantages of the along-track data acquisition system is that the<br />

images creating the stereopairs are obtained a few seconds apart under consistent lighting<br />

and environmental conditions, producing a stereopairs of homogeneous quality that are<br />

suitable for generating DEMs employing automated stereocorrelation techniques (Hirano<br />

et al. 2003) (figure 3.1). ASTER is capable of producing 771 digital stereopairs per day<br />

(Lang and Welch 1999, Welch et al. 1998). To produce a stereo pair image, there is about<br />

a 60-second interval between the time the ASTER nadir telescope passes over a ground<br />

location and the backward telescope (27.6° or 27.7° off nadir) records the same location<br />

on the ground path of the satellite. By that time, the satellite travels an estimated distance<br />

of 370km over the earth’s surface (ground speed is 6.7km/sec) producing the 60km stereo<br />

scene (Chrysoulakis 2004, Fujisada 1994, Hirano et al. 2003, Kamp et al. 2003, Lang et<br />

al. 1996, Lang and Welch 1999, Toutin 2001, Welch et al. 1998), as shown in figure 3.2.<br />

Figure 3.1: Simplified diagram of imaging geometry and data acquisition timing for<br />

ASTER along-track stereo image (From Welch et al. 1998, figure 2, p. 1283).<br />

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Figure 3.2: Simplified diagram of the imaging geometry for ASTER along-track stereo<br />

image “stereo configuration” (From Hirano et al. 2003, figure 1, p. 358).<br />

3.4. Obtaining ASTER imagery data<br />

The choice of satellite imagery mostly depends on the availability of data for a<br />

certain location, time, price, and the required scale of the application (Poli et al. 2005).<br />

ASTER imagery was specifically chosen in this research for four main reasons: (1) its<br />

worldwide coverage (2) the capability of generating DEMs from its stereo images, (3)<br />

high quality ground resolution of 15m which is suitable for landforms identifications, and<br />

finally (4) the affordable prices of ASTER images per scene.<br />

ASTER satellite images are available at the United States Geological Survey<br />

(USGS) website (http://glovis.usgs.gov) that easily allows browsing, purchasing, and<br />

downloading satellite data. Multiple sensors are listed as separate links enabling viewing<br />

and purchasing of scenes utilizing the USGS global visualization viewer, they can be<br />

done by visiting the desired sensor link. ASTER data are available at a separate link<br />

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(http://glovis.usgs.gov/ImgViewer/ImgViewer.html?lat=&lon=&mission=ASTER&senso<br />

r=ASTERVNIR) and scenes are provided as mosaics each show the acquisition date, its<br />

unique reference number, longitude and latitude, satellite path and row, and cloud cover<br />

percentage as illustrated in figure 3.3.<br />

Figure 3.3: The USGS global visualization viewer showing ASTER scenes of Jordan.<br />

Four ASTER Level-1B data scenes of the same swath with 14 spectral bands were<br />

purchased representing the Gulf of Aqaba (one scene), Wadi Araba (two scenes), and the<br />

Dead Sea (one scene) in Jordan. The browser allows choosing from multiple satellite<br />

platforms and scenes acquired in different years and seasons of nearly the entire world.<br />

The satellite data chosen for the study area were acquired in September 16, 2002 with a<br />

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zero percent (0%) cloud cover for the entire four scenes. The four ASTER scenes were<br />

delivered as a Pull-FTP site sent through email after ordering. The total price is 225 USD<br />

with a price of US $55 for each scene and US $5 data processing and handling (Kamp et<br />

al. 2003, 2005, Poli et al. 2005). Table 3.1 shows the area coverage of ASTER imagery of<br />

Jordan-Dead Sea Transform Zone (JDTZ) area and the type of data products (i.e.<br />

granules) and their reference numbers listed from north to south.<br />

The coordinates for all ASTER images for areas around the world are recorded in<br />

the Universal Transverse Mercator (UTM) coordinate system in meters and referenced to<br />

the World Geodetic System of 1984 (WGS-84) ellipsoid (Hirano et al. 2003, Lang et al.<br />

1995, Lang and Welch 1999, Fujisada 1998, Fujisada et al. 2001).<br />

Area coverage Data Type Granule/Product Cost<br />

The Dead Sea ASTER L1B registered SC: AST_L1B.003:2008495456 $55<br />

radiance at the sensor V003<br />

North Wadi Araba ASTER L1B registered SC: AST_L1B.003:2008495466 $55<br />

radiance at the sensor V003<br />

South Wadi Araba ASTER L1B registered SC: AST_L1B.003:2008495566 $55<br />

radiance at the sensor V003<br />

Aqaba ASTER L1B registered<br />

radiance at the sensor V003<br />

SC: AST_L1B.003:2008495567 $55<br />

Table 3.1: ASTER scenes selected to cover the JDTZ study area.<br />

3.5. Viewing ASTER data in PCI Geomatica<br />

PCI Geomatica software (Geomatica 2003) facilitates working with imagery,<br />

vectors, graphical bitmaps, and other geospatial using its Focus application. Focus is a<br />

visual environment with many useful display tools that enables viewing, editing, and<br />

enhancing remotely sensed data of a variety of satellite sensors and aerial photography.<br />

All data is stored together as the native PCIDSK file format using a single file name<br />

extension of PIX that contains all features and database tables. Moreover, the image data<br />

are stored as channels and auxiliary data are stored as segments which makes it easier for<br />

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the PCI Geomatica software application tools to perform searching, sorting, and<br />

recombining operations of such data type (Geomatica 2003).<br />

Viewing ASTER images begins with starting up Geomatica Focus from the<br />

Geomatica Toolbar (figure 3.4). To view any ASTER images, the first step would<br />

normally be to import the HDF files using Geomatica Focus into PCIFDSK then save<br />

them as *.PIX format. In Focus window, File> Utility> Import to PCIDSK. Next browse<br />

for the source file and set the options to default. Then chose the ASTER sensor<br />

instrument needed to create the image from (in this case VNIR) and click OK (figure<br />

3.5). Finally, set the output file destination path then click Import (figure 3.6).<br />

Figure 3.4: Focus is the first icon on the Geomatica Toolbar.<br />

Figure 3.5: Selecting ASTER VNIR sensor images.<br />

Figure 3.6: Import File window.<br />

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To view the final imported ASTER VNIR PIX image(s) composite in Focus<br />

window, select File> Open> and navigate to the *.PIX file location. Other methods to<br />

view the ASTER PIX image would be adding three layers of different bands to create the<br />

composite image [Layer> Add> RGB> bands 3N, 2, and 1> Finish]. Both methods will<br />

convey the same results as shown in figure 3.7.<br />

Figure 3.7: ASTER 3-2-1 color composite image of Aqaba recorded to the UTM<br />

coordinate system and referenced to WGS-84 ellipsoid.<br />

3.6. Generating ASTER DEMs<br />

In this section, the processes of generating ASTER DEMs and all associated<br />

stages such as importing/exporting and converting satellite images, creating epipolar<br />

images, generating and editing final DEMs, and photogrammetric software involved in<br />

the process are explained in details and depicted in figures. In addition, an in-depth detail<br />

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of the process of obtaining Landsat 7 enhanced thematic mapper plus (ETM+) images<br />

and vector data to facilitate digitizing mountain fronts and related valleys to calculate the<br />

S mf and V f geomorphic index values is also explained.<br />

3.6.1. Generating and extracting DEMs from ASTER data<br />

3.6.1.1. PCI Geomatica software<br />

PCI OrthoEngine software is an efficient photogrammetric tool that handles a<br />

wide range of dataset formats with the capability to produce quality geospatial products<br />

(Geomatica 2003). OrthoEngine supports reading of ASTER data, ground control points<br />

(GCPs) collection, geometric correction, ortho-rectification, DEM generating and<br />

modeling, and either manual or automatic mosaicking. In addition, this software also has<br />

the capability to automatically generate DEMs from either aerial photographs or satellite<br />

stereoscopic sensors (Geomatica 2003, Toutin and Cheng 2001). PCI OrthoEngine<br />

software was developed at the Canada Center for Remote Sensing (CCRS), Natural<br />

Resources in Canada. Currently, this software is extensively used by the NASA EOS<br />

Land Processes Distributed Active Archive Center (DAAC) located at the USGS EROS<br />

Data Center to produce EOS Standard Product DEMs from stereo ASTER data (Toutin<br />

and Cheng 2001).<br />

In the process of DEM extraction, the selection of very important points known as<br />

tie points (TPs) is common in DEM manual processing. Usually, manual selection of<br />

points produces low quality DEMs with a lot of redundant or irrelevant information<br />

potentially being lost, which is omitted when using automated DEM extraction. The basic<br />

conditions necessary for generating an accurate DEM are: (1) using high accuracy control<br />

points, and (2) using enough tie points to guarantee error control dependability (Cuartero<br />

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et al. 2004). Commonly, the use of accurate tie points will speed up and would result in<br />

significant enhancement of the DEM generation process (Lang and Welch 1999, Selby<br />

2003), as the quality of TPs is crucial for the final DEM quality (Kamp et al. 2003). Tie<br />

points can be chosen manually or automatically and are used to refine the relative<br />

orientations of the stereo images. This is the triangulation process and once it is complete,<br />

the DEM is created by finding conjugate points in the stereo pair in a manner similar to<br />

automatic tie point finding but much, much more dense. The tie points then guide the<br />

DEM point finder enabling it to better find DEM points (figures 3.8 and 3.27).<br />

Figure 3.8: Comparing raw images to epipolar images (From Geomatica 2003, figure 6.2,<br />

p. 69).<br />

OrthoEngine allows work with specific modules for large set of spatial data<br />

including ASTER. The influence of software is very obvious in terms of DEM results.<br />

The PCI Geomatica software includes an ASTER specific model that compensates for the<br />

shortage of orbital parameters that uses the ephemeris and attitude information recorded<br />

in the ASTER metadata which accordingly produces better-quality DEMs (Cuartero et al.<br />

2004, Geomatica 2003, Lang and Welch 1999). Basically, the ASTER satellite orbital<br />

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math model is able to compensate for the effects of varying terrain and for the distortions<br />

inherent to the camera. Such parameters include the curvature of the lens, the focal<br />

length, the perspective effects, and the camera’s position and orientation. In addition, the<br />

calculated math model calculates the camera’s position at the time when the images were<br />

taken (Geomatica 2003).<br />

In case of ASTER data products, the software uses a minimum of six tie pints (or<br />

GCPs) located in both 3N and 3B images to generate a pair of epipolar images in order to<br />

retain elevation parallax in only one direction (i.e. y-axis, N-S direction). Epipolar images<br />

are stereo pairs that are reprojected to have a common orientation and matching features<br />

between the right and left stereo images (Geomatica 2003, Selby 2003). Then an<br />

automatic image-matching procedure is used to produce the DEM through a comparison<br />

of the individual gray values of these images. This procedure utilizes a hierarchical subpixel<br />

normalized cross-correlation matching method to find the corresponding pixels in<br />

the left and tight epipolar images. The difference in location between images gives the<br />

parallax arising from the terrain relief, which is then converted to elevation values above<br />

the local mean sea level of the given datum (Geomatica 2003, Lillesand et al. 2004,<br />

Toutin and Cheng 2001). Figure 3.9 is a simplified scheme showing the algorithm for<br />

measuring height (∆h) from parallax difference in an ASTER stereopairs where B is the<br />

base and equals to X 1 . For the nadir (vertical-looking) and the aft (backward-viewing)<br />

cameras configuration, ∆h is related to the camera orientation angle (α) and the time<br />

interval (∆t) required to record both the top and the bottom of the object, which is<br />

represented by (X 1 -X 2 ) = ∆p in the nadir/aft stereopair (Lang and Welch 1999).<br />

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Figure 3.9: Measuring height from ASTER stereopair parallax difference (From Lang and<br />

Welch 1999, figure 2.0-3, p. 13).<br />

PCI Photogrammetric software uses automatic stereo image correlation approach<br />

to extract DEMs by calculating the parallax differences from ASTER 3N and 3B<br />

channels (Chrysoulakis et al. 2004, Lang and Welch 1999, Poli et al. 2005). This method<br />

is able to automatically produce relative DEMs from ASTER stereopairs in PCI<br />

OrthoEngine tool using simply tie points to adjust the images together (Chrysoulakis et<br />

al. 2004, Kamp et al. 2003). In this research both TPs and GCPs were utilized in<br />

generating epipolar stereopairs and in turn the final DEMs for the JDTZ. The use of TPs<br />

alone has the advantage of speeding up the process but the accuracy for the resulting<br />

DEM will be inferior to the one created using both GCPs and TPs. Once any TPs and<br />

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GCPs have been collected, then a bundle adjustment operation is performed to computes<br />

a photogrammetric model using the orbital and sensor ephemeris information, plus the<br />

GCPs and TPs, so that images are located relative to each other and to the ground (Lang<br />

and Welch 1999, Selby 2003). The only difference between these points’ types is that<br />

TPs are used to match points to relate stereo images to each other, which can be<br />

calculated either manually or automatically. While GCPs are used to adjust the images to<br />

the shape and orientation of the earth’s surface which typically come from an<br />

independent source such as GPS.<br />

The process of generating DEMs using PCI Geomatica software requires the<br />

construction of a stereo pair by registering two images of the same ground area recorded<br />

from different positions in space. Any positional differences in the stereo pair that are<br />

parallel to the direction of satellite travel (i.e. parallax difference) are attributed to<br />

displacements caused by relief on the ground (figure 3.9). Relative ground elevations are<br />

determined by measuring the parallax difference in the registered images that eventually<br />

are converted to relative or absolute (if GCPs available) elevations (z-coordinate values)<br />

in the final DEM (Lang and Welch 1999). The specifications of a standard ASTER DEM<br />

data product are illustrated in figure 3.10 and table 3.2.<br />

Standard ASTER DEM Products<br />

Unit of coverage 60km x 60km ASTER Scene<br />

Format<br />

Elevations in meters; UTM; WGS-84<br />

Resolution X-Y = 15, 30m, or 90m; Z = 1m<br />

Product Name GCP Accuracy DEM Accuracy<br />

Relative DEM None 10-30m<br />

Absolute DEM 15-30m (or 5-15m) 15-50m (or 7-30m)<br />

Table 3.2: Specification for standard ASTER DEM products (Modified from Lang and<br />

Welch 1999, table 3.0-1, p. 19).<br />

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Figure 3.10: Summary of a standard ASTER DEM product generation process (Modified<br />

from Lang and Welch 1999, figure 3.0-2, p. 17).<br />

3.6.1.2. DEMs extraction process<br />

Whatever the image data are used, the main digital processing steps for DEM<br />

generation are: (1) setting-up the stereo images, (2) data extraction by image matching,<br />

(3) the 3D stereo intersection, and (4) the DEM editing (Toutin 2001). In this research,<br />

some guiding principles were followed for DEM generation that includes: (1) generating<br />

DEMs automatically, if possible, with minimal manual intervention to reduce induced<br />

inaccuracy, (2) GCPs were only exploited to match the JDTZ generated DEMs to<br />

GTOPO30 based on the satellite ephemeris data, no elevation values were used due to the<br />

lack of such data from the source, (3) coarse DEM GTOPO30 database are utilized to fix<br />

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possible missing data within generated ASTER DEMs, and (4) DEMs of 30m grid are<br />

generated (Fujisada et al. 2001, Tokunaga et al. 1996).<br />

The extraction of ASTER DEMs process is explained in more details in the<br />

literature provided by Geomatica (2003, chapter 6) and Selby (2003). These tutorials<br />

illustrate the relative straightforward procedures of the automatically extraction of DEMs<br />

and orthorectified images from ASTER satellite imagery utilizing PCI Geomatica<br />

OrthoEngine. The output of the automatic extraction of ASTER images is orthorectified<br />

DEM and images which are automatically geocoded that can be used with other datasets<br />

and to orthorectify other images within ASTER files or other satellite images (Selby<br />

2003). The step-by-step DEM extraction methods derived from ASTER purchased<br />

images of the JDTZ study area in addition to all input options and final editing are<br />

explained in this section.<br />

All of the L1B data (and L1A data) are basically stored together with metadata in<br />

one HDF file (Abrams et al. 2003, Abrams and Hook 2002, Selby 2003). The stereo<br />

images corresponding to bands 3N and 3B are extracted from the original hierarchical<br />

data format (HDF) file in PCI Geomatica 9.1 environment. Both channels have different<br />

size due to the different detector size (Chrysoulakis et al. 2004, Fujisada 1994, Fujisada<br />

et al. 1998, Poli et al. 2005).<br />

In general, ASTER L1B VNIR subsystem dataset band 3N has 4200 (rows) x<br />

4980 (columns) pixels and band 3B has 4600 (rows) x 4980 (columns) pixels (Abrams et<br />

al. 2003). Therefore, the ground coverage in across-direction is the same, while in the<br />

along-track direction, the scene 3B covers a longer area than 3N (Poli et al. 2005). A time<br />

delay occurs between the acquisition of the backward-viewing image and the nadir<br />

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image. During this time Earth rotation displaces the image center. The VNIR subsystem<br />

automatically extracts the correct 400 pixels based on the orbit position information<br />

supplied by the EOS platform. The pixels of 400 lines on band 3B equals to about 8.7%<br />

of the whole band 3B image, plus both sides shift. The estimated 3N and 3B overlap area<br />

is approximately 85% of the image area (JPL, personal communication).<br />

For the georeferencing of all ASTER imagery the position and attitude of the<br />

sensors at the acquisition time of each image line is required. The metadata contained in<br />

the HDF file supplied this information (Poli et al. 2005).<br />

-Step One: Create a new project<br />

Initially click the OrthoEngine icon on the Geomatica 9.1 Toolbar to start<br />

OrthoEngine (figure 3.11). Creating a new project starts with opening a new file from the<br />

OrthoEngine File menu. Each ASTER scene in the study area requires a separate project,<br />

thus, four projects were created for this purpose. Then, construct a new project from the<br />

processing step drop-down menu (figure 3.12). After that, the software gives the option to<br />

read the satellite data from a variety of data storage media such as CD-ROM, hard drive,<br />

or a tape (figure 3.13). This will lead to a new window where the project information<br />

needs to be entered. After filling in the filename and the project description in the<br />

designated boxes, the next step would be choosing the math modeling method and setting<br />

up the options. The options include the high resolution satellite being used to create the<br />

DEMs from; in this case ASTER was selected (figure 3.14).<br />

Figure 3.11: OrthoEngine (4 th icon) on the Geomatica Toolbar.<br />

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Figure 3.12: Opening new project from the processing step drop-down menu.<br />

Figure 3.13: Reading satellite data from hard drive using the 3 rd icon.<br />

3.6.1.3. The math model<br />

The math model is the mathematical relationship used to correlate the pixel of the<br />

used satellite image to correct locations on the ground considering know distortions. The<br />

math model directly impacts the outcome of the final project; therefore, choosing the<br />

correct model that matches the imaging sensor is essential. The satellite orbital math<br />

modeling is a rigorous model developed to compensate for distortion cause by sensor<br />

geometry, orientation, and integration time, satellite orbital and altitude variations, earth<br />

relief, shape, and rotation, the platform position, velocity, and orientation. The ASTER<br />

math model principally calculates the position and orientation of the sensor at the time<br />

the images were taken. The accuracy of the ASTER satellite orbital math model is about<br />

one-third of a pixel in the VNIR satellite images (Geomatica 2003).<br />

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Figure 3.14: Project Information window including project name and setting the<br />

mathematical model method and the satellite options.<br />

Afterward, the output projection for the output DEM and orthoimages should be<br />

set as a first step (Geomatica 2003, Selby 2003) to UTM zone-36: 30E to 36E, Row: R-<br />

24N to 32N, and WGS-84 ellipsoid (D-000-Global Datum Definition or Ellipsoid E012).<br />

Since ASTER VNIR data are used to generate the DEMs, the output pixels spacing<br />

should match the used 3N and 3B bands which is set to 15m. In the presence of GCPs, it<br />

is recommended to set their projections based on the output file, as shown in figures 3.15<br />

to 3.19.<br />

Figure 3.15: Setting project projection to UTM.<br />

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Figure 3.16: Setting the UTM zones.<br />

Figure 3.17: Setting the UTM rows.<br />

Figure 3.18: Setting Earth Model (Ellipsoid).<br />

Figure 3.19: Setting GCPs to match the output file projection.<br />

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Finally, the project is ready to read the raw ASTER data HDF files in order to<br />

process the stereo images and create the DEMs (figure 3.20). Select both 3N and 3B<br />

bands to be read and create 3N.pix and 3B.pix and their resultant report files 3N.rpt and<br />

3B.rpt, respectively. Then provide an output filename for each band. It is important to<br />

read band 3N first as one file then band 3B as another. The reason for not reading them<br />

into a single file is due to the different pixel/line size of band 3B to band 3N (Selby<br />

2003).<br />

Figure 3.20: Reading row ASTER data HDF files from the hard drive.<br />

-Step Two: Collecting ground control points and tie points<br />

Selecting the right number and the best ground control points locations directly<br />

affect the satellite orbital math model and eventually the accuracy and quality of the<br />

generated DEMs. It is essential to choose features that are recognized accurately at the<br />

resolution of the raw image. To improve the accuracy of the output DEMs generated<br />

from ASTER images the minimum GCPs recommended are six points per image,<br />

however, collecting more than the minimum number of points uniformly throughout the<br />

images ensure the overall DEMs accuracy (Geomatica 2003).<br />

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All images have 121, evenly spaced GCPs with x and y locations on the ground.<br />

However, the z-values are not provided, thus, all elevation values are not available and<br />

shown as zero. These GCPs coordinates included with the ASTER scene are calculated<br />

from the sensor and ground processing and are used to transfer these values to the<br />

ground. They are only as accurate as the satellite ephemeris information. To view the<br />

existing GCPs, choose the import GCPs from file icon (figure 3.21), then select image 3N<br />

(similar GCPs number in image 3B) to load the available GCPs on the image (figure<br />

3.22). The 121 GCPs are evenly distributed in a grid form over the entire image of each<br />

ASTER scene as shown in figures 3.23 to 3.25.<br />

Figure 3.21: Importing GCPs from file using the 8 th icon on the toolbar.<br />

Figure 3.22: loading the 121 already available GCPs from image 3N file.<br />

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Figure 3.23: Dead Sea band 3N GCPs.<br />

Figure 3.24: Dead Sea band 3B GCPs.<br />

Figure 3.25: The image layout of bands 3N and 3B showing the location of all 121 GCPs<br />

in the Dead Sea ASTER image.<br />

The following step in the process is collecting tie points which aims to adjust and<br />

correlate the two stereo images together. Using tie points allows automatic extraction of<br />

the DEM from the generated 3N and 3B images only (figure 3.262). However, the<br />

addition of GCPs to these images will permit precision geocoding and scaling of DEMs<br />

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in the z direction (Selby 2003). Tie points are basically features that are clearly<br />

recognizable in two or more images and can be used as reference points to identify how<br />

images relate to each other (Geomatica 2003), as illustrated in figure 3.27.<br />

Figure 3.26: Start the Collect Ground Control Points (GCPs) and Tie Points (TPs)<br />

manually function from bands 3N and 3B by using the 2 nd icon on the OrthoEngine<br />

toolbar.<br />

Figure 3.27: An image shows how two images connect through a tie point (From<br />

Geomatica 2003, figure 5.2, p. 51).<br />

Selecting a set of quality tie points (minimum of six) which are spread over the<br />

images is vital to the accuracy of the final DEMs. Therefore, tie points should be features<br />

that can be accurately identified at the resolution of the raw image. It is important to<br />

choose tie points that are close to the ground and away from features that rise above the<br />

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ground such as buildings and mountains because high features may appear to lean in one<br />

image but may not in the other. In addition, shadows are not suitable to be used as tie<br />

points since they are not a permanent feature and may move from one image to another.<br />

Streets and highways intersection are the best features to be selected as tie pints since<br />

they are permanent feature and easy to identify in the images (Geomatica 2003).<br />

To start collecting tie points manually (figure 3.28), both images should be active<br />

during this process where the one from which points are being collected would be labeled<br />

Working while the other is labeled Reference (figure 3.29). After choosing a single tie<br />

point from the working image, it is easy to collect the same point in the other image by<br />

switching to the reference image and select the same point. All tie pints are recorded in<br />

the tie point collection window (figure 3.30 and table 3.3). It is highly recommended to<br />

zoom in to see the detail in the image and use both Auto Locate and Bundle Update<br />

features during tie point collection. The auto locate feature is employed by OrthoEngine<br />

to estimate the position of the points by using an automatic correlation method once it has<br />

adequate information to calculate the math model. Usually, this function works best when<br />

there are three tie points existing per image. On the other hand, the bundle update feature<br />

allows OrthoEngine to perform the bundle adjustment every time a tie point is added to<br />

the project. This can assist to determine the dependability of the point being selected for<br />

the project (Geomatica 2003).<br />

Figure 3.28: Collecting tie points manually from both images by choosing the 9 th icon on<br />

the OrthoEngine toolbar.<br />

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Figure 3.29: Opening both uncorrected 3N and 3B images to manually collect tie points.<br />

Figure 3.30: Collecting tie point window for Aqaba image 3N including the type of tie<br />

point, their residual errors, their x, y coordinates, and z values on each image.<br />

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DEM Coverage Area Dead Sea North Araba South Araba Aqaba<br />

Number of tie points 24 23 17 20<br />

Manual tie points (T) 20 18 11 15<br />

Automated tie points (AT) 4 5 6 5<br />

Table 3.3: Number and type of tie points in each DEM coverage area.<br />

When done collecting tie points manually, running the Automatically Collect Tie<br />

Points from the 10 th icon on the GCP/TP Collection list of the OrthoEngine (figure 3.31)<br />

using the default inputs increase the chances of finding more tie points to enhance the<br />

overall DEM resolution. Since tie points are simply matching points in two images,<br />

collecting points can be automated in OrthoEngine utilizing image correlation techniques.<br />

On the automatic tie point collection window, setting the tie point distribution pattern will<br />

enable better automatic tie point matching. The number of tie points per area was set to<br />

nine points to be distributed uniformly over the entire image. While the matching<br />

threshold that indicates the minimum correlation score that will reflect a successful<br />

match, which is represented by any value ranging from zero indicating no correlation to<br />

one signifying the best correlation has been set to 0.75 (Geomatica 2003, Selby 2003), as<br />

demonstrated in figure 3.32. Further extensive information regarding image correlation<br />

principles and image matching techniques can be found for instance in (Ebner and<br />

Heipke 1988, Förstner 1992, Hannah 1988, Heipke 1996, 1992, 1989, Mahn 1989).<br />

Figure 3.31: Automatically Collect tie points.<br />

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Figure 3.32: Automatically Collect tie points uniformly over an entire image.<br />

On the tie point collection window (figure 3.30), the residual error indicates the<br />

residual difference in pixels between the coordinates that were entered for the tie points, a<br />

typographical mistake, or an error in the position of the tie points on the raw image.<br />

Typically, for every tie-point a 3D point on the ground is computed. This 3D ground<br />

point is reprojected through the rigorous ASTER math model to a new image coordinate.<br />

All the tie points are used to estimate the exterior orientation of the stereopair and so the<br />

reprojected 3D point will not fall exactly where you measured it. Residual errors do not<br />

necessarily reflect errors in the tie points, but rather the overall quality of the math model.<br />

Such errors might denote bad points, but usually they indicate the quality of the<br />

computed math model to fit the ground control system. In general, high residual errors<br />

suggest a poor model solution which is a result of inaccurate tie points, errors of the<br />

projection or datum, inadequate tie points, or unsatisfactory distribution of the tie points<br />

over the image (Geomatica 2003).<br />

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Figures 3.33 and 3.34 show tie points in both 3N and 3B image of the North<br />

Araba area. The T indicates manual tie point while TA indicates an automated tie pint<br />

collection. Finally, to view the distribution of the collected tie pints within the 3N and 3B<br />

images, choose the display overall image layout from the 11 th icon on the OrthoEngine<br />

GCP/TP Collection list toolbar as in figures 3.35 and 3.36.<br />

Figure 3.33: Band 3N tie points (North Araba). Figure 3.34: Band 3B tie points (North<br />

Araba)<br />

Figure 3.35: Displaying overall image layout from both images.<br />

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Figure 3.36: Image layout of both bands 3N and 3B for the North Araba scene.<br />

-Step Three: Math model calculations<br />

Once all of tie points have been collected from stereo images, then a bundle<br />

adjustment ought to be performed to compute the photogrammetric model using the<br />

orbital and ASTER sensor ephemeris information in addition to tie points and GCPs if<br />

available (Geomatica 2003, Selby 2003). The bundle adjustment uses the tie points and<br />

the knowledge of the sensor geometry and orientation to calculate the best fit for all<br />

images used in the project to generate the DEM simultaneously (Geomatica 2003), as<br />

shown in figure 3.37.<br />

Figure 3.37: Running Model Calculation to perform bundle adjustment.<br />

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-Step Four: Creating epipolar images<br />

As mentioned earlier, OrthoEngine uses image correlation to extract matching<br />

pixels in the two stereo images and they apply the season geometry computed from the<br />

math model to calculate the x, y, and z positions, as shown in figure 3.38. Epipolar<br />

images are stereo pairs that are reprojected in order that the left and the right images have<br />

an ordinary orientation, and matching features within the images appear a long a common<br />

x axis. The main purpose of creating epipolar images is to eliminate any offset between<br />

them in the y axis direction. Besides, epipolar images accelerate the autocorrelation pixel<br />

matching algorithm and process that creates DEMs exploiting the stereo overlap area<br />

between the epipolar images and diminish the possibility of incorrect matches due to the<br />

fewer pixels it searches to find a match (Geomatica 2003, Selby 2003).<br />

Figure 3.38: Creating a DEM from stereo pairs using image correlation (From Geomatica<br />

2003, figure 6.1, p. 69).<br />

To create epipolar images start with initiating the Create epipolar image window,<br />

which is the 1 st icon located under the DEM from Stereo list on OrthoEngine toolbar<br />

(figure 3.39). Using the User Select option will allow the manual selection of the stereo<br />

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pairs for each DEM to be extracted. In the left and right image window, normally band<br />

3N is assigned as the left image while band 3B to the right. After that, add the 3N and 3B<br />

stereo images to the Epipolar Pairs Table using all channels. Then select epipolar images<br />

from the List of Epipolar Pairs and set the working cache to at least 256MB, then click<br />

save setup to store all entered options. Finally, click on the Generate Pairs button to start<br />

the epipolar images generating process (Geomatica 2003) (figure 3.40).<br />

Figure 3.39: Create Epipolar image icon.<br />

Figure 3.40: Generate Epipolar images window.<br />

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-Step Five: Extracting DEMs<br />

Automatic DEM extraction is the final step in the DEM generating process.<br />

Starting the function using the 2 nd icon on the OrthoEngine toolbar under DEM from<br />

Stereo list (figure 3.41) will launch the Automatic DEM extraction window (figure 3.42).<br />

To finalize the extraction process, the output DEM file requires a name and a path to be<br />

saved to. Afterward, choose all images in the DEM Bounds to use the extents of all the<br />

images in the Stereo Pair Selection table as the extents of the DEM then click the<br />

Recompute icon to adjust the image size, the DEM resolution (30m), and recalculate<br />

extents, then finally click Start DEM Extraction to generate the geocoded DEM file<br />

(Geomatica 2003). Table 3.4 summarizes the options used in DEM automatic extraction<br />

of all epipolar images for the study area. All elevations were based on the topographic<br />

maps of southern Jordan available at scales of 1:50,000, 1:100,000, and 1:250,000.<br />

Figure 3.41: Extract DEM Automatically icon.<br />

DEM Coverage Area Dead Sea North Araba South Araba Aqaba<br />

Minimum Elevation -650m -600m 0m 0m<br />

Maximum Elevation 1800m 1950m 1800m 1800m<br />

Failure Value -600 -9998 -100 -100<br />

Background Value -9999 -9999 -150 -150<br />

DEM Detail Medium Medium Medium Medium<br />

Output DEM Channel Type 16-bit Signed 16-bit Signed 16-bit Signed 16-bit Signed<br />

Pixel Spacing Interval<br />

(DEM resolution)<br />

2 (30m) 2 (30m) 2 (30m) 2 (30m)<br />

Fill Holes and Filter Yes Yes Yes Yes<br />

Create Score Channel Yes Yes Yes Yes<br />

Create Geocoded DEM Yes Yes Yes Yes<br />

Table 3.4: Options used for all DEMs extraction processes within the study area.<br />

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Figure 3.42: Automatic DEM extraction window showing all used options for Aqaba<br />

DEM.<br />

Failures in the DEM extraction occur in areas with very low contrast such as<br />

shadows, clouds, snow, and water bodies. Usually, small failure holes in the DEM are<br />

filled automatically by interpolation, while large failure areas necessitate manual editing<br />

using filters to complete the DEM (Selby 2003). Specifying failure values is very useful<br />

when interpolating these pixels in subsequent DEM editing. The Background value<br />

categorizes the pixels with no data that lies outside the extracted DEM overlap area so<br />

they could be distinguished from elevation values. Alternatively, the maximum and<br />

minimum elevations are employed to estimate the search area for the correlation, which<br />

increase the speed of the correlation process and reduce error (Geomatica 2003).<br />

Therefore, due to the high contrast between the mountains and valleys elevations in the<br />

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North Araba and the Dead Sea images, the minimum and maximum elevation values in<br />

these areas have been expanded by ±150m to enable enhanced DEM results.<br />

The Fill Holes and Filter option is used to enhance the quality of the DEM<br />

product by automatically filtering the elevation values and interpolating the failed areas.<br />

Also, turning on the Create Score Channel option generates an extra image channel that<br />

classifies the failed pixels during correlation to the ground for each DEM pixel, which<br />

assist evaluating the success of the procedure. Finally, choose the Create Geocoded DEM<br />

to merge and geocode the epipolar DEMs (Geomatica 2003).<br />

During DEM extraction, image correlation is used to locate similar features on<br />

both the left and right stereo images. Matching these features is normally achieved by a<br />

hierarchical approach utilizing a pyramid of reduced resolution images. This method<br />

creates a multi-resolution image pyramid that consists of a base image and a series of<br />

sequentially smaller sub-images, each at half the resolution of the previous image (figure<br />

3.43). This correlation technique expedites the image correlation operation and<br />

diminishes the mismatches measures. The first correlation attempt is executed on very<br />

coarse versions of the images. This facilitates OrthoEngine matching major features by<br />

precisely constructing the foundation for advanced correlation attempts. The next<br />

attempts are carried out on higher resolution images until finally the correlation is<br />

performed on images at full resolution to provide the highest accuracy of the terrain in<br />

the DEM (Geomatica 2003, Ismert et al. 2003).<br />

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Figure 3.43: The multi-resolution image pyramids method of creating reduced resolution<br />

images to optimize display performance (Modified from Ismert et al. 2003, figure 5, p.<br />

6).<br />

3.6.1.4. DEMs editing process<br />

During the DEM extraction process few missing data and little failure holes with<br />

unsatisfactory resolution were produced in dispersed locations. Most failure holes are a<br />

few meters wide, the largest is about 4.5km across located in South Araba area. The<br />

interpolation of ASTER data normally solves such problems by restoring the failure holes<br />

of 1km or lees with elevation values. In this case, since there are several failure holes of<br />

dissimilar sizes that were scattered randomly in the highest and lowest elevation areas<br />

within the JDTZ, the procedure of editing DEM were applied to substitute for these<br />

missing data.<br />

These missing data occurred when using the full resolution DEM (pixel sampling<br />

of 1, yielding 15m DEM) due to the high contrast in elevation of the terrain relief<br />

between mountains and valleys. Nevertheless, the major mountains and valleys in the<br />

study area are identifiable and well defined to proceed with digital geomorphic analysis.<br />

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Thus, medium DEM detailed resolution (pixel sampling of 2, yielding 30m DEM) was<br />

generated, which is suggested for most satellite images to accelerate the process and<br />

produce smooth DEMs (Geomatica 2003). Due to the geographic nature of the JDTZ, it<br />

was difficult to recognize and allocate mutual features in both epipolar images during the<br />

process of generating DEM. Therefore, employing the full resolution 15x15m pixel<br />

sampling window increased the probability of image-to-image correlation failure creating<br />

many and larger failure holes that were fewer when using the medium 30x30m pixel<br />

sampling window. Since ASTER is an optical sensor, it is impossible to generate DEMs<br />

in cloud-covered areas or water areas (Tokunaga 1996); as a result, both the Dead Sea<br />

and the Mediterranean Sea show no elevation data. The generated geocoded 30m<br />

resolution DEMs for each ASTER scene are presented in figures 3.44 to 3.47, where the<br />

missing data can be noticed as black holes (i.e. no data) within the DEMs.<br />

Figure 3.44: The Dead Sea generated DEM. Figure 3.45: North Araba generated DEM.<br />

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Figure 3.46: South Araba generated DEM.<br />

Figure 3.47: Aqaba generated DEM.<br />

Following the generation of the DEM, editing can be performed, if required, to<br />

correct out and fill in the failures and missing data. Consequently, the final DEMs and<br />

orthorectified images are valuable for interpretation and analyses of landforms and<br />

geology (Selby 2003). The DEM editing process necessitates another DEM data source in<br />

order to retrieve the missing data. Usually GTOPO30 coarse DEM data is used due to its<br />

global coverage (Fujisada et al. 2001). The DEMs editing method using both Geomatica<br />

Focus and XPace Tools are explained below in details.<br />

-Step One: Importing and subsetting the global DEM<br />

In order to fix the missing data in the generated DEMs of the study area, coarse<br />

DEM data of known elevation values is being used. The global DEM GTOPO30 image<br />

of the Middle East with a horizontal grid spacing of approximately 1km (Campbell 2002)<br />

and has a file extension of HDR is accessible from the USGS website available at<br />

(http://edcdaac.usgs.gov/gtopo30/dem_img.asp), as shown in figure 3.48.<br />

1. Importing the GTOPO30 DEM to PCI Geomatica 9.1 and convert the image<br />

to *.PIX with a new file name and path [File> Utility> Import to PCIDSK><br />

GTOPO30.HDR> file name].<br />

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2. Subsetting the whole Middle East GTOPO30 DEM to fit the JDTZ study area.<br />

Using Tools in Focus window [Tools> Clipping/Subsetting> Enter file name><br />

Set dimensions to subset].<br />

-Step Two: Reprojecting the global DEM<br />

The GTOPO30 DEM data is projected as latitude/longitude, thus, to best fit the<br />

study area the DEM needs reprojection to the UTM zone-36: 30E to 36E, Row: R-24N to<br />

32N, and WGS-84 (E012) ellipsoid.<br />

1. To do so, in Focus [Tools> Reprojection> Enter the GTOPO30 file name> Set<br />

the projection parameters> Resampling = Nearest> Transform Order = Exact><br />

Sampling interval = 1> Source layer = All> Reproject].<br />

-Step Three: Adding New Channels<br />

1. All DEM scenes should be viewed as Pseudocolored images to facilitate<br />

editing, this is done in Focus window as follow: [Layer> Add><br />

Pseudocolored> File name].<br />

2. Adding new channels to each study area scene should be done before starting<br />

fixing any of the DEMs.<br />

3. One bitmap channel that is specified using the special symbol (%%) and two<br />

raster 16-bit signed channels, which is specified using the special symbol (%)<br />

should be added for each DEM file (signed channel allow reading data as<br />

integers of ± values).<br />

4. On the maps tree menu, click on file to add extra channels to the exiting DEM<br />

files [Right click on the file name> New> Raster Layer x2] then repeated the<br />

same step for the Bitmap Layer.<br />

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Figure 3.48: General view of the clipped GTOPO30 DEM of the Middle East showing<br />

the JDTZ study site (Map not to scale).<br />

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-Step Four: Filling the missing values in the study area DEMs<br />

1. This step aims to fill in the missing values of each DEM of the study area by<br />

known values obtained from the GTOPO30 DEM.<br />

2. Using XPace Tool from the Geomatica toolbar (figure 3.49).<br />

3. Each DEM file of the study area is separately combined with GTOPO30 DEM<br />

by performing image mosaicking using the Geometric Correction package and<br />

Image Mosaicking task as follow: [XPace> Geometric Correction> Image<br />

Mosaicking]. Normally, a mosaic composite image is made of joining together<br />

individual images covering adjacent regions on the ground (Campbell 2002,<br />

Sabins 1997). Thus, mosaicking process is basically piecing together several<br />

contiguous, overlapping, or bordering images to ultimately create a uniform<br />

image (Geomatica 2003).<br />

4. Filling the parameters window as indicated below then RUN the application.<br />

FILI: (GTOPO30 DEM file name)<br />

OBIC: 1<br />

FILO: (study area DEM file name)<br />

OBOC: 2<br />

Where FILI indicates the name of the PCIDSK file (i.e. DEM) from which the<br />

input image data is to be read. FILI cannot be the same as FILO, because the bounds of<br />

the two images stored in their georeferencing segment are needed to determine their<br />

overlap, OBIC is the input channel(s) with integer numbers to read from input files on<br />

FILI and stored to output file on FILO, and OBOC is the output channel(s) on FILO to<br />

write the image data to (Geomatica 2003).<br />

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5. Remove all files from the maps tree menu and then reload again as<br />

pseudocolored layers [for each DEM in the study area load only channel 2<br />

(%2)].<br />

6. Repeat procedure 3 to 5 for each of t he four DEMs.<br />

Figure 3.49: The XPace Tool, the 10 th icon on Geomatica Toolbar.<br />

-Step Five: Creating a mask for the missing values<br />

A mask categorizes specific pixels over areas that need editing. Normally, the<br />

mask doesn’t change the values in the areas that it covers, although it assists in<br />

identifying these areas to be replaced with true (or known) elevations from other sources<br />

(Geomatica 2003).<br />

1. Using the EASI modeling to create a mask to the already created bitmap<br />

channel (%%2). In Focus window [Tools> EASI Modeling> Enter file name<br />

of the study area DEM].<br />

2. Run the EASI modeling using the following syntax:<br />

if % 1 = (enter the failed value of each study area DEM e.g. -9998) then<br />

%% 2 = 1<br />

else<br />

%% 2 = 0<br />

endif<br />

-Step Six: Filling the missing values within the mask<br />

1. Using the EASI modeling to create a mask to the already created bitmap<br />

channel (%%2) and the new raster channel (%2). In Focus window, [Tools><br />

EASI Modeling> Enter file name of the study area DEM].<br />

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2. Run the EASI modeling using the following syntax:<br />

if %% 2 = 1 then<br />

% 1 = % 2<br />

else<br />

% 1 = % 1<br />

endif<br />

3. Remove all images from the maps tree menu and reload the first channel (%1)<br />

of the study area DEM.<br />

-Step Seven: Smoothing the mask and finishing up the whole DEM scene<br />

Filtering of missing data within DEMs will eventually alter the original elevation<br />

values. Thus, filtered portions of the DEMs are used for as a cosmetic procedure for<br />

display purposes and not as an elevation source for the morphometric analysis.<br />

Smoothing the mask was done by utilizing convolution filters which involve the<br />

movement of filter window throughout an image pixel-by-pixel and line-by-line until<br />

covering the whole image. Low pass filter enhances remotely sensed images by blocking<br />

the high spatial frequency details utilizing different size mask of a particular brightness<br />

value and outputs a new images with new brightness values. The size of the mask varies<br />

but usually 3 x 3, 5 x 5, 7 x 7, or 9 x 9 window. A low pass images for each DEM were<br />

produced using a 9 x 9 averaging function mask. Ultimately, the central pixel value<br />

within the mask is replaced by an average of the surrounding nine pixels in the<br />

convolution filter (Campbell 2002, Jensen 1996, 2004, Mather 1999, Moore and Waltz<br />

1993, Sabins 1997).<br />

1. This process is achieved using XPace Tool.<br />

2. Using Average Filter to smooth the mask of the added pixel values for<br />

GTOPO30 DEM due to their coarser resolution compared to the ASTER<br />

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DEM resolution using Image Processing package and Average Filter (FAV)<br />

task [XPace> Image Processing> FAV].<br />

3. Run the application after entering the following data in the parameters<br />

window:<br />

FILE: (file name of the study area DEM)<br />

DBIC: 1<br />

DBOC: 1<br />

FLSZ: 9, 9<br />

MASK: 2<br />

Where FILE is the input DEM file of, DBIC specifies the input channel to be<br />

filtered, DBOC specifies the output channel for the filtered result, FLSZ is the filter size<br />

in units of pixels and lines, in this case a filter size of 9 x 9 pixels/lines window is used,<br />

and MASK indicates the area in the input channel which should be processed, in this case<br />

use the bitmap channel (%%2) to only process pixels under it (Geomatica 2003).<br />

-Step Eight: Loading final DEM<br />

Remove all images from the maps tree menu then reload the raster channel (%1)<br />

of each DEM in the study area. At this point, the DEMs should be completely fixed and<br />

ready to be transferred as an ASCII file to be readable in ArcScene program within the<br />

ArcGIS software for further analyses. The difference between the generated ASTER<br />

30m-pixel resolution DEM(s) and the coarser pixels of the 1Km resolution mask derived<br />

from GTOPO30 DEM could be notices as shown in figures 3.50 to 3.53. Four transfers<br />

are needed for each repaired DEM where only channel (%1) of each fixed DEM being<br />

transferred. This procedure is carried out in Focus window as follow: [File> Utility><br />

Translate> Browse: DEM File name> Destination> Type new DEM ASCII File Name><br />

GRD: Arc/Info Grid (ASCII) as the new file extension].<br />

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Figure 3.50: The Dead Sea final DEM.<br />

Figure 3.51: North Araba final DEM.<br />

Figure 3.52: South Araba final DEM.<br />

Figure 3.53: Aqaba final DEM.<br />

3.6.1.5. Transferring ASTER DEM to GIS environment<br />

GIS has the capability to integrate multiple map layers including DEMs and<br />

satellite imagery and run several analyses to the spatial relationship within these maps<br />

quickly and with no effort (Horsby and Harris 1992). In addition to that, viewing data in<br />

three dimensions in GIS environment give new perspective about the derived DEM data,<br />

adding insights that wouldn’t be readily visible from a planimetric view (Poli et al. 2005).<br />

The three dimensional vector and raster data and DEMs generated in ArcGIS depicting<br />

DEMs and digitized valleys and mountain fronts were imported to ArcScene for further<br />

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analysis and visualization. Particularly, ArcScene application available with ArcGIS<br />

(ESRI) 3D Analyst extension, allows creating three dimensional maps for visualization<br />

and rendering with a static level of detail control for large datasets (Chrysoulakis et al.<br />

2004, Poli et al. 2005). The incorporation of elevation and terrain data, generally,<br />

improves the management and visualization of geographic data and can enhance<br />

information extraction (Poli et al. 2005). Thus, the developed three dimensional DEM<br />

views using ArcScene will represent the high quality of the generated DEMs and their<br />

potential for more thorough image interpretation (Kamp et al. 2003).<br />

Converting the DEM ASCII files to raster files in the form of ESRI GRID format<br />

to be readable by ArcGIS software and its extensions is achieved using a specific<br />

command line for this purpose. The Command Line window is located under the Window<br />

tab in the ArcMap main menu (within the ArcGIS 9 software). The command line is<br />

simply identifies the current ASCII file format location and convert it into a grid file<br />

format to the same or another path creating a floating-point raster dataset. Floating-point<br />

number (or real number) is a sort of numeric field used for measuring and for storing real<br />

number that can contain a fractional part and a decimal point (e.g. 34.824, 0.0004, and -<br />

9873.21). The decimal point can be in any position in that field, thus, there is no fixed<br />

number of digits before and after the decimal point, that is, the decimal point can float<br />

from one place to another for different valued stored in the filed (Mather 1999). To<br />

perform conversion, insert the following case sensitive command line<br />

ASCIIToRaster_Conversion <br />

FLOAT. An example of the Dead Sea DEM<br />

conversion using this command line would be ASCIIToRaster_Conversion<br />

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C:\All_DEMs\aster_dem_D-S.ascC:\All_DEMs\aster_dem_D-S_newFLOAT. After this<br />

conversion, the DEM data can be imported to GIS environment for any further analysis,<br />

as illustrated in figures 3.54 and 3.55.<br />

Figure 3.54: Portion of the North Araba converted GRID file format (*.GRD) to ASCII<br />

format, notice the failure value (-9999) on the top and the elevation values on the rest of<br />

the file.<br />

Figure 3.55: The converted North Araba DEM using ArcGIS ASCII to Raster command<br />

line.<br />

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3.7. Obtaining Landsat 7 ETM+ imagery<br />

The Landsat imagery could be obtained and downloaded free of charge from the<br />

University of Maryland Institute for Advanced Computer Studies website provided by the<br />

Global Land Cover Facility, Earth Science Data Interface available at<br />

(http://glcf.umiacs.umd.edu/index.shtml). When clicking the “Download Data” button<br />

located on the upper-right part of the screen, a new webpage that has all the available<br />

satellite sensors scenes will appear. For the purpose of this research, Landsat 7 ETM+<br />

sensor was chosen to download the imagery of the JDTZ study area in Jordan that is<br />

available at (http://glcfapp.umiacs.umd.edu:8080/esdi/index.jsp).<br />

Two Landsat scenes were downloaded that cover the study area located within the<br />

JDTZ. Each image carries a unique identification number and the size of the image as<br />

follow: The Dead Sea ETM+ image data is (p174r038_7x20020308.ETM-EarthSat-<br />

Orthorectified) and the Wadi Araba ETM+ image data is (p174r039_7x20020308.ETM-<br />

EarthSat-Orthorectified). The data acquisition date of both scenes is March 8, 2002 and<br />

the data processing date is February 12, 2004. All Landsat data are in the form of<br />

compressed files (*.gz file extension) that are downloadable from the FTP files site<br />

available at (http://glcfapp.umiacs.umd.edu:8080/esdi/ftp?id=37264) where each Landsat<br />

band could be individually downloaded from the FTP link denoted for each band. The<br />

final Landsat imagery is a georectified TIFF images that are projected to the WGS-84<br />

datum and ellipsoid and are compatible with all ESRI GIS products.<br />

3.7.1. Creating ASTER and Landsat composite images<br />

To view and analyze both ASTER and Landsat images in a GIS environment, the<br />

images would be more informative and useful if they are in the form of a color composite<br />

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image. The best combination of three bands of Landsat satellite imagery forming a false<br />

color image of an arid to semiarid region would be 7, 4, and 2 as Red, Green, and Blue,<br />

respectively (Arlegui and Soriano 1998). Toward the differentiation between the Landsat<br />

and ASTER color composite images, the former sensor images were displayed as 7-4-2<br />

composites while the latter as 3-2-1 true color composite images. Having two different<br />

color combination of satellite images will allow flipping back and forth between the<br />

images, which will assist in highlighting mountain fronts and valleys in the digitizing<br />

process and accentuating the differences between the different color image combinations.<br />

The procedures to create color composite images from Landsat and ASTER scenes area<br />

as follow:<br />

-Step One: Import images to the new composite image file<br />

The creation of a composite image depends firstly on the input file initial format.<br />

In case the input image in PIC format there is no need to perform importing, otherwise,<br />

the common Landsat and ASTER images formats such as HDF and/or TIFF need to be<br />

imported to PCIDSK format.<br />

a) Importing the HDF or TIFF files to PIX files first using PCI Focus (File><br />

Utility> Importing to PCIDSK> Source File Name> Destination File Name> Import).<br />

b) In XPace, use the PIX file that you created in the first step as an input to the<br />

composite image that you need to produce. Make sure to import and transfer files in the<br />

order desired to create the composite image (RGB). If an image composite of bands 1, 2,<br />

and 3 needed, then, import band 3 (Red) first, then transfer bands 2 (Green) and 1 (Blue)<br />

respectively. (File> File Utility> Importing to PCIDSK> type the Source File Name><br />

enter the Destination File Name (the name of the RGB composite final image)> Import).<br />

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-Step Two: Transfer imported images<br />

a) In XPace, transfer the other two layers (bands Green and Blue) to the imported<br />

PIX file (the Red band already exists) in step 2. The process is carried out as follow:<br />

(Tools> Transfer Layers> enter the Source File Name (band Red from step 2)> type in<br />

the Destination File Name (band Green)> Select the new image> Add> Select the added<br />

image> Transfer Layers).<br />

b) Repeat the same procedures as in the previous step (2/a) for the last layer (band<br />

Blue).<br />

-Step Three: Create the final composite image<br />

a) In Focus, open the created composite RGB image. Right click on the image><br />

Enhance> Edit LUTs> Click on the Red band histogram once> Save> Save image<br />

w/LTU> Overwrite existing channel> OK). Repeat the same procedures for the other<br />

Green and Blue band histograms.<br />

Lookup tables (or LUTs) consist of an array of the original input pixels and the<br />

corresponding array of enhanced output pixels values that are used to produce the new<br />

composite image. It contains the exact disposition of each combination of red, green, and<br />

blue (RGB) values associated with each 8-bit pixel. Normally, the color of each pixel in<br />

the image is determined by matching it to a set of colors stored in tables that show their<br />

numerical values. Usually there are three LUTs for each of the composite color that is<br />

presented in the form of a graphic display or a histogram (Campbell 2002, Jensen 1996,<br />

2004, 2004, Mather 1999, Sabins 1997). Whereas, histogram is known as a statistical<br />

graph represents the distribution of data points and content of a remotely sensed image as<br />

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a function of some attribute, such as brightness values (Campbell 2002, Jensen 1996,<br />

2004, 2004, Mather 1999, Sabins 1997).<br />

-Step Four: Transfer the final composite image to new format<br />

a) In Focus, transfer the created composite image to TIFF or JPG using (File><br />

Utility> Translate> Source File Name> Destination File Name> Set output format as<br />

TIF/TIFF 6.0> Select all source layers> Add> Select all destination layers> Export). By<br />

the end of this process the final satellite images are ready to be imported to ArcGIS<br />

software and viewed as raster layer with the same projection as of the vector data in the<br />

map project.<br />

3.8. Obtaining vector data<br />

The vector data were obtained from the Digital Chart of the World (DCW). The<br />

scale of the thematic dataset or layers is 1:1,000,000 (or 1cm: 10km), which was<br />

produced in 1993 (Campbell 2002). All layers are compatible with any geographic<br />

information system (GIS) software in the market. The downloaded coverages data are in<br />

interchange file format (*.E00 file extension) originally designed for ArcInfo that is also<br />

readable by ArcView and ArcMap. Interchange files could be converted into coverage<br />

file and in turn into Shapefiles using ArcToolbox, and then by using the projection tool<br />

we can define the coordinate system (e.g. WGS-84) to the Shapefiles. The original DCW<br />

data is projected to geographic longitude/latitude and to decimal degrees and the entire<br />

database is provided by Penn State University Libraries webpage available at<br />

(http://www.maproom.psu.edu/dcw/).<br />

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3.8.1. Converting Interchange files to Shapefiles in ArcToolbox<br />

In order to import the vector data into any GIS environment, the data should be<br />

readable by such software. The downloaded interchange files from the DCW much be<br />

converted into a compatible file format, namely shpafiles, to be loaded into the GIS<br />

software. The steps of converting interchange files to shapefiles are listed below.<br />

-Step One: Importing interchange files (*.00E)<br />

-Under Import to Coverage use the Import from interchange file tool (figure 3.56).<br />

-Browse to input the needed interchange file (in this case road layer was selected)<br />

and assign the output file name and path, then click OK to execute file conversion.<br />

-The result of this conversion is a coverage file of the actual interchange file.<br />

Coverage is a vector-based data storage file that usually represents a single theme and<br />

used to store the location, shape, and attributes of geographic features. It is one of the<br />

main and native vector data formats for ArcGIS that combines spatial data and attribute<br />

data and stores topological relationship among features. Normally, coverage file saves<br />

spatial data in binary files and attribute and topological data is kept in tables. The related<br />

feature attribute tables normally describe and store attributes of the geographic features<br />

(Zeiler 1999).<br />

Figure 3.56: Import from Interchange file window in ArcToolbox.<br />

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-Step Two: Convert Coverage to Shapefile (*.shp)<br />

-Under Export from Coverage use the Coverage to Shapefile tool (figures 3.57<br />

and 3.58).<br />

-Navigate to the roads coverage file created in the previous step to serve as the<br />

input file. Set the feature type to line. Then give the shapefile output file name and path,<br />

and then click OK to perform file conversion using default setting.<br />

-The output file is a shapefile that represents the roads of Jordan.<br />

Figure 3.57: The Coverage to Shapefile tool in ArcToolbox.<br />

Figure 3.58: The Coverage to Shapefile tool window in ArcToolbox.<br />

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-Step Three: Defining Shapefile projection<br />

-Under Projections tool use the Define Projection Wizard (shapefile, geodatabase)<br />

(figure 3.59).<br />

-Browse to the input file (i.e. roads shapefile), highlight the file in the data<br />

window and then click next (figure 3.60).<br />

-Select the coordinate system that suites the study area to be assigned to the input<br />

data then click OK to complete. The coordinate system was set to the spheroid-based<br />

Clarke Geographic Coordinate Systems of 1866 (i.e. spatial reference). This is the default<br />

projection of the downloaded interchange files which is the only projection that is wellsuited<br />

the UTM Projected Coordinate Systems of WGS-84, zone-36 North. The finale<br />

shapefile is ready to be imported into ArcGIS to overlay other layers and images or for<br />

any further analyses.<br />

Figure 3.59: The Define Projection Wizard in ArcToolbox.<br />

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Figure 3.60: The Define Projection Wizard window under Projections in ArcToolbox.<br />

3.8.2. Digitizing vector data<br />

Obviously, as a result of the scale difference between the vector data obtained<br />

form the DCW (scale 1:1,000,000) and the satellite imagery (scale 1:50,000), some<br />

editing to the vector data was necessary to match significant features on the satellite<br />

imagery. Toward this, the shapefiles of Jordan western borders and the Dead Sea<br />

shorelines boundaries (figure 3.61) were modified, as close as possible, to fit the similar<br />

features on ASTER imagery using the Editor tool that exists in ArcMap software.<br />

On the other hand, the capitals and major cities in all of the produced maps were<br />

manually digitized as points. Capital and major cities of the surrounding countries to<br />

Jordan were digitized utilizing the seismic map of the Middle East (Chapter 1, figure<br />

1.22), while the major Jordanian cities were manually digitized using the geologic maps<br />

of Jordan. The digitized points were first created in ArcCatalog as point shapefile and<br />

then projected to the UTM zone-36N and to the WGS-84 ellipsoid. Using the Editor tool<br />

available within the ArcMap software, the capitals and cities were digitized over each<br />

point on the designated map that indicate each location.<br />

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Figure 3.61: Map shows the Dead Sea shoreline (left) and Jordan borders (right) before<br />

(red line) and after (gray line) editing.<br />

3.8.3. Digitizing mountain fronts and measuring sinuosity<br />

Due to the relatively large imagery sizes and the presence of various mountain<br />

fronts and valleys within the study area dictate large processing time, digitizing, and<br />

computations will be performed on a scene-by-scene basis (Lang and Welch 1999). To<br />

increase the possibility of recognizing mountain fronts and valley profiles within the<br />

study area, shaded relieves (Hillshades) of each of the ASTER DEM scenes were created.<br />

Towards this, exchanging the view back and forth between the DEMs and shaded relieves<br />

took place during digitizing mountain fronts and valley profiles process. Shaded relieves<br />

were generated using the 3D Analyst tool in ArcMap based on the elevation data<br />

available in each ASTER DEM scene. In 3D Analyst, pick the raster layer needed to be<br />

generated as shaded relief then click on Surface Analysis and choose Hillshade. Browse<br />

to the destination DEM in the Hillshade window and use default values for both azimuth<br />

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and altitude and 30m for the output cell size. Select a destination to save the Output<br />

shaded relief raster then generate by clicking the OK button. Repeat the same process for<br />

all ASTER DEM scenes, as shown in figure 3.62, an example from the Gulf of Aqaba<br />

area.<br />

Figure 3.62: The Gulf of Aqaba generated DEM (left) and shaded relief (right).<br />

Prior to digitization process it is necessary to create two new polylines (i.e. lines)<br />

shapefiles for each ASTER scenes area using ArcCatalog. One of these lines represents<br />

the vector layer of the mountain fronts and the other serves as the straight front lengths of<br />

each mountain front. The digitization of mountain fronts sinuosity and their<br />

correspondent total straight lengths were based entirely on the criterion mentioned in<br />

section (3.2.1). Using the digitization tool, each mountain front was created<br />

independently, in some cases, pixel-b-pixel to get as close as possible to the mountain<br />

front in each scene of the imagery, until finishing all available fronts in each scene.<br />

Figures 3.63 to 3.74 illustrates the ASTER color composites (3-2-1 as RGB), derived<br />

ASTER DEMs, generates shaded relieves, digitized mountain fronts and valley profiles<br />

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of each individual ASTER scene in the JDTZ. The overall number of mountain fronts in<br />

the study area are listed in table 3.5 and illustrated in figure 3.75.<br />

Geomorphic form Dead Sea North Araba South Araba Aqaba<br />

Fronts 1 1 4 9<br />

Table 3.5: Overall number of digitized fronts in the JDTZ.<br />

Figure 3.63: Dead Sea ASTER color composite 3-2-1.<br />

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Figure 3.64: Dead Sea ASTER-derived DEM.<br />

141


Figure 3.65: Dead Sea shaded relief.<br />

142


Figure 3.66: North Araba ASTER color composite 3-2-1.<br />

143


Figure 3.67: North Araba ASTER-derived DEM.<br />

144


Figure 3.68: North Araba shaded relief.<br />

145


Figure 3.69: South Araba ASTER color composite 3-2-1.<br />

146


Figure 3.70: South Araba ASTER-derived DEM (portion of the North Araba and Aqaba<br />

DEMs are shown to the north and south, respectively, to cover the fronts and valleys<br />

extension).<br />

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Figure 3.71: North Araba shaded relief (portion of the North Araba and Aqaba shaded<br />

relieves are shown to the north and south, respectively, to cover the fronts and valleys<br />

extension).<br />

148


Figure 3.72: Aqaba ASTER color composite 3-2-1.<br />

149


Figure 3.73: Aqaba ASTER-derived DEM.<br />

150


Figure 3.74: Aqaba shaded relief.<br />

151


Figure 3.75: An overall map of the mountain fronts and valley profiles within the JDTZ.<br />

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The achieved calculations of both values were computed in meters without human<br />

intervention using XTools Pro. This appropriate tool provides an accurate length and<br />

elevation measurements (in addition to many other features) and delivers the results in<br />

the form of columns added directly to the specific shapefile attribute table. The XTools<br />

Pro is a freeware ArcMap add-on provided by Data East GIS software development that<br />

functions as any other ArcMap extension and is available to download at<br />

(http://www.xtoolspro.com/). To calculate all lengths using this tool, the XTools Pro<br />

main drop-down menu use the Table Operations, then Calculate Area, Perimeter, Length,<br />

Acres and Hectares. After that a new window appears asking to enter the shapefile need<br />

to be calculated and the desired outcome units. This process creates new columns in the<br />

selected shapefile’s attribute table demonstrating the exact calculated lengths of both<br />

sinuosity and straight length for each mountain front. Finally, calculating the S mf values<br />

for all mountains is achieved by feeding all the data into a Microsoft Excel spreadsheet<br />

and program the mountain front sinuosity formula to compute the final values.<br />

3.8.4. Digitizing valley profiles and measuring elevations and valleys’ widths<br />

After valleys were being identified in the study area, the digitizing process or their<br />

profiles took place. Quite similar to mountain fronts digitization procedure, the digitizing<br />

tool was used to create a straight two dimensional line -that will be turned into a three<br />

dimensional profile in subsequent steps- covering the valley and the mountain peaks on<br />

both sides. Based on the criteria of choosing valley profiles mentioned in section (3.2.2),<br />

all valleys were digitized according to their visual identification that was entirely<br />

restricted to the generated DEMs resolution. The number of the digitized valleys and the<br />

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minimum and maximum valley profiles distances upstream from associated mountain<br />

fronts are listed in table 3.6.<br />

Distance Dead Sea North Araba South Araba Aqaba<br />

Valleys # 22 15 25 36<br />

Minimum 150m 220m 215m 45m<br />

Maximum 2500m 2500m 1100m 1100m<br />

Table 3.6: Digitized valley profiles number and their distances upstream from mountain<br />

fronts in the JDTZ.<br />

When creating valley profile shapefiles in ArcCatalog, it is important to check the<br />

Coordinates will contain Z values box to enable the shapefiles to store three dimensional<br />

data. The three dimensional data generally has an extra z-value for each x,y coordinate<br />

that is typically used to store the vertical height of the coordinate. The z-values can be<br />

viewed and modeled using the ArcGIS 3D analyst extension, in addition the converted<br />

valley profile three dimensional shapefiles would be rendered using ArcScene program to<br />

measure the main three elevations of each valley (i.e. E ld , E rd , and E sc ). The digitization of<br />

valley profiles will serve the purpose of calculating the four unknown elevations of E ld ,<br />

E rd , E sc and V fw values in order to calculate the V f values of each individual valley.<br />

Towards this, the valley profiles will be first converted into a two dimensional cross<br />

section profile to calculate the V fw values. Then, all the valley profiles will be converted<br />

into three dimensional profiles and viewed in ArcScene to measure the elevation values<br />

of each valley individually. Since all the valleys in the study area run approximately in<br />

the east-west direction, as a result, the valley profiles are all oriented in the north-south<br />

direction. Therefore, during the calculation of the V f values, the north end of each valley<br />

profile will represent the east elevation of the valley divide (E ld ), while the south end will<br />

represent the right valley elevation divide (E rd ).<br />

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To calculate the V fw values of each individual digitized valley, the “Create Profile<br />

Graph” located in the ArcGIS 3D Analyst extension is being employed to create a profile.<br />

This graph-like profile will have x and y that symbolize terrain distance and elevation,<br />

respectively. Setting the DEM of the related area to the valley profiles being graphed is a<br />

crucial step to acquire the exact ground measurements. Simply, clicking on the Create<br />

Profile Graph button enables drawing a straight line over each already digitized valley<br />

shapefile. After completing drawing all valley profiles in a specific ASTER DEM<br />

imagery, the drawn profiles could be viewed as graphs by double click on each individual<br />

profile. As illustrated in figure 3.76, the valley floor width can be calculated by<br />

subtracting the values of the beginning and ending of the valley floor using the reference<br />

distance on the x-axes.<br />

Figure 3.76: Calculating the V f value for valley profile #11 in the Dead Sea area (green<br />

and red lines manually added for illustration purposes).<br />

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To collect the right and left divide and floor (i.e. E ld , E rd , and E sc ) elevation values<br />

of each individual digitized valley, the 3D Analyst “Convert Features to 3D” tool being<br />

utilized. This tool and the conversion procedure allow deriving existing features height<br />

from a surface. For the purpose of this research, the study area generated ASTER DEMs<br />

are being used as the surface to obtain elevation data from. The Convert Features to 3D<br />

process allows the manually digitized polyline, which represent each valley profiles, to<br />

mimic the topography of the valley using the elevation data of the DEM to create a 3D<br />

profile of the actual landscape, as illustrated in figure 3.77.<br />

Figure 3.77: The difference between the (a) 2D image (straight-line) and (b) the actual<br />

3D topography (dotted-line) of a given surface (Modified from ArcGIS Desktop Help,<br />

Linear Interpolation).<br />

The process of conversion two dimensional (2D) shapefile to three dimensional (3D)<br />

features in 3D Analyst is as follow:<br />

1. Add the shapefile of each individual valley profile, which is in the form of a<br />

two dimensional feature and the elevation reference surface to an existing map<br />

in ArcGIS.<br />

2. Click 3D Analyst and choose Convert, and then click Features to 3D.<br />

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3. Locate the valley profile shapefiles that need to be converted into 3D in the<br />

Input Features menu.<br />

4. Click the Raster or T<strong>IN</strong> Surface button and set the source to the Valley<br />

profiles related DEM (i.e. raster data) to gather the features heights.<br />

5. Type the name of the output 3D shapefile and allocate a destination.<br />

6. Finally, Click the OK to execute.<br />

Following the conversion all valley profiles in to 3D features in the study area, the<br />

three dimensional shapefiles need to be converted into points. This important additional<br />

step is performed using the XTools Pro in order to assign each point in the 3D shapefile<br />

to its matching elevation value on the ground. The way this method function is by<br />

collecting the elevation value from the center of each pixel in the DEM where the<br />

polyline passed through (figure 3.78). From the XTools Pro main menu, simply choose<br />

“Feature Conversions”, and then Convert Features to Points. This tool is provides ArcGIS<br />

users with capabilities to convert polygons and polylines to point features with<br />

customizable options. The conversion process is explained below and illustrated in<br />

figure 3.79.<br />

Figure 3.78: Collecting elevations from DEM as shapefile passes raster (a) horizontally,<br />

(b) diagonally, and (c) vertically.<br />

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1. In ArcGIS, add all valley profiles of a single ASTER DEM scene at the time<br />

into the map.<br />

2. Select the "Convert Features to Points" item from the XTools Pro Feature<br />

Conversions menu.<br />

3. From the drop-down list select the “Input feature layer” and select the valley<br />

profiles shapefiles (i.e. polylines) for one of the four DEMs in the study area<br />

to be converted to points.<br />

4. Assign a destination and name to the output layer file to be saved in a<br />

shapefile format, then press the OK button.<br />

Figure 3.79: Converting Aqaba 3D feature to points using XTools Pro.<br />

After performing all point conversions, the XTools Pro “Table Operations” is<br />

being used to translate the created data points of each individual three dimensional<br />

shapefiles into readable tables. From the XTools Pro main menu, choose the Table<br />

Operations option, and then click the “ADD X, Y, Z Coordinates”. After that, a new<br />

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window will appear asking to enter one of the already converted 3D-shapefiles into<br />

points to create provide their X, Y, and Z values. The elevation values are created in the<br />

form of additional three data fields automatically added to the correlated shapefile<br />

attribute tables.<br />

The developed 3D valley profiles exhibit the highest quality of the generated<br />

DEMs in identifying the geomorphologic forms and providing extra details of the exact<br />

points of collecting essential elevation data. Hence, they are best viewed using ArcScene<br />

to extract the elevation values of E ld , E rd , and E sc for each valley in the study area (3.80).<br />

After importing all valley profile 3D shpafiles and DEMs of the study area into<br />

ArcScene, collecting the elevation data (i.e. z-values only) of E ld , E rd , and E sc of each<br />

profile is performed using the information button located in the main toolbar, as<br />

illustrated in figure 3.81. After obtaining the elevation data from the entire valley profiles<br />

in all four DEMs within the study area, this information combined with the already<br />

calculated data of the V fw values of all valleys from the previous step are transferred into<br />

Microsoft Excel spreadsheet. Utilizing the function tool in Excel, the V f equation is being<br />

programmed to perform an automated calculation of the V f values for the entire valley<br />

profiles in the study area.<br />

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Figure 3.80: General view from the Dead Sea area (Looking east, hillshade shows 2xelevation<br />

exaggeration, map not to scale).<br />

160


Figure 3.81: Collecting elevation data from profile #11 in the Dead Sea area (Looking<br />

east, DEM shows 2x-elevation exaggeration, map not to scale).<br />

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4. Chapter Four: Results and Discussion<br />

4.1. Introduction<br />

The geomorphic analysis of landscape forms exhibits a great potential for<br />

assessing the tectonic activity of the JDTZ. Theoretically, the morphometric analysis of<br />

mountain front sinuosity (S mf ) and valley floor width to valley height ratio (V f ) indicate<br />

the tectonic activity of the mountain front and its adjacent province. Generally, in arid to<br />

semiarid regions, lower values are associated with V-shaped valleys and reflect high<br />

tectonic activity while higher values are linked to U-shaped valleys indicating a moderate<br />

to low tectonic activity (figure 4.1).<br />

Figure 4.1: Valley profile display of a V-shaped valley in South Araba (left) and a U-<br />

shaped valley in the Dead Sea area (right).<br />

In this chapter the results of the geomorphic indices derived from each ASTER<br />

scene in the JDTZ will be individually discussed and the tectonic activity categories of<br />

the study area presented and discussed. The tectonic activity classes of all mountain<br />

fronts and valley profiles were initially designated based on the tectonic activity ranges<br />

established by Bull and McFadden (1977). Such categorization was adopted because it<br />

has proven to be practical in various regions of different geologic settings. Finally, the<br />

accuracy of the ASTER-derived DEM will be tested based on the elevation accuracy of<br />

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the ASTER satellite data provided in the literature in order to examine their reliability<br />

and effect on the final S mf and V f results. Therefore, the results of these indices will be<br />

examined and compared with the valley profile shapes to generate appropriate tectonic<br />

activity classes of the analyzed landforms in the study area.<br />

4.2. The tectonic morphometric analysis<br />

In previous research (chapter two, section 2.3), none of these studies specified a<br />

precise method of differentiating tectonic activity classes. In contrast, the study<br />

conducted by Bull and McFadden (1977) illustrates a significant overlapping in all of the<br />

three tectonic classes. This research aims to generate discrete ranges of the tectonic<br />

activity classes of both S mf and V f results. Furthermore, the three tectonic activity classes<br />

of the valley profiles were determined entirely according to the assigned tectonic activity<br />

class based totally on the S mf values of the mountain front that these valleys are<br />

associated with. Therefore, in this research the definition of each tectonic class will not<br />

only rely on the S mf calculated values of individual mountain fronts but also will be<br />

derived from the individual valley profile V f results.<br />

Table 4.1 lists concise results of both mountain front sinuosity (S mf ) and the<br />

valley floor width/height ratio (V f ) computations. The tectonic activity classes of the V f<br />

index results are assigned based on the V f mean values as presented in previous studies<br />

(Bull and McFadden 1977, Rockwell et al. 1984, Silva et al. 2003, Wells et al. 1988).<br />

Despite the length of the mountain front of the Dead Sea area that is connected to the<br />

North Araba mountain front, it is still fits the criterion of being a continuous mountain<br />

front and will be considered as one entity referred to as the Dead Sea and North Araba<br />

mountain front. In this regard, both mountain fronts were initially measured separately to<br />

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check their individual S mf and V f values then were measured as a single mountain front in<br />

the subsequent morphometric analysis computations. Detailed results of all S mf and V f<br />

calculations and description of individual valleys shapes are presented in appendix A, and<br />

illustrated in figure 4.2.<br />

Fronts/Valleys Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

# of Valley<br />

Profiles<br />

V f<br />

Mean<br />

Dead Sea 1 67.70 1.07 1 22 0.54 1<br />

North Araba 1 64.63 1.21 1 15 0.50 1<br />

Dead Sea & North Araba 1 132.32 1.14 1 37 0.53 1<br />

South Araba<br />

Aqaba<br />

V f<br />

Mean<br />

Class<br />

1 35.94 1.16 1 6 0.56 1<br />

2 3.62 1.21 1 2 0.75 1 - 2<br />

25<br />

3 32.14 1.28 1 15 0.35 1<br />

4 15.26 1.17 1<br />

2 0.47 1<br />

1 10.52 1.12 1 2 0.16 1<br />

2 14.60 1.22 1 3 0.32 1<br />

3 12.03 1.21 1 2 0.43 1<br />

4 19.98 1.71 2 4 0.67 1 - 2<br />

5 8.07 1.17 1 36 1 0.55 1 - 2<br />

6 10.12 1.07 1 2 0.18 1<br />

7 10.62 1.22 1 4 0.14 1<br />

8 21.31 1.25 1 10 0.26 1<br />

9 22.30 1.13 1<br />

8 0.21 1<br />

Table 4.1: Brief results of all mountain fronts sinuosity (S mf ) and valleys floor width to<br />

valleys height ratio (V f ) analyses.<br />

164


Figure 4.2: The tectonic activity classes of the S mf and V f indices results.<br />

165


4.2.1. Mountain front sinuosity results<br />

The mountain front sinuosity analysis shows the lowest results as 1.07 of two<br />

mountain fronts in both the Dead Sea and Aqaba regions and the highest S mf result as<br />

1.71 in the Aqaba region. The results of the S mf analysis of all mountain fronts within the<br />

JDTZ study area indicate that the majority of mountain fronts are highly tectonically<br />

active representing the tectonic activity class 1. On the other hand, only one mountain<br />

front (front 4) in the Aqaba region yield S mf result of 1.71 which symbolizes the moderate<br />

to low tectonic activity class 2. This particular circumstance might have occurred as a<br />

result of the following two principal reasons. (1) The ASTER satellite imagery and the<br />

generated DEM of the Aqaba region did not extend to cover the total length of mountain<br />

front number 4. Therefore, the analysis of the partial length of the mountain front<br />

sinuosity could not provide the actual S mf value precisely. (2) The mountain front has<br />

experienced modification to its shape due to the prolonged erosion caused by the seasonal<br />

flash floods often occurred in this area causing it to be more sinuous (USGS 1998), where<br />

the latter explanation is interpreted to be the main cause.<br />

4.2.2. The ratio of valley floor width to valley height results<br />

The ratio of the valley floor width to valley height analysis reveals the lowest<br />

value as 0.09 in the Aqaba region while the highest V f result as 1.24 in the South Araba<br />

region. Theoretically, the U-shaped valleys indicate relatively low tectonic activity, while<br />

the V-shaped valleys, as a response to uplift, are associated with high tectonic activity<br />

(Bull 1977b, 1978, Bull and McFadden 1977, Burbank and Anderson 2001, Keller and<br />

Pinter 2002). To examine the relationship between the valley profile shapes and tectonic<br />

166


activity, the percentage of the U- and V-shaped valley profiles were calculated and<br />

summarized in table 4.2.<br />

Valley shape/region Northern region Southern region<br />

U-shaped valley 9/37 = 24.4% 26/61 = 42.6%<br />

V-shaped valley 28/37 = 75.6% 35/61 = 57.4%<br />

Table 4.2: The percentage of the U- to V-shaped valley profiles in the JDTZ.<br />

The valley shape percentage calculations were carried out based on dividing the<br />

JDTZ study area into two regions the southern (South Araba and Aqaba) and northern<br />

(Dead Sea and North Araba) regions with a total of 61 and 37 valleys, respectively. The<br />

separation of the study area into two regions had been implemented due to the<br />

continuation and overlapping of a number of fronts into other adjoining areas (e.g. Dead<br />

Sea into North Araba and South Araba into Aqaba). This method of dividing the study<br />

area into two regions based on the spatial distribution of the mountain fronts and their<br />

initial morphometric analysis was adopt by Rockwell et al. (1984) and Wells et al. (1988)<br />

and found to be valuable for the final evaluation of the tectonic activity classes of the<br />

mountain fronts in these regions. Evidently, the V-shaped valleys in both regions are<br />

abundant, however, the U-shaped valleys in the southern region are more frequent<br />

(42.6%) showing a higher percentages (almost twice the value) in comparison to the<br />

northern region (24.4%) signifying a moderate to less tectonic activity in that particular<br />

region.<br />

Practically, it would be quite difficult to distinguish which area is more<br />

tectonically active than the other since the majority of S mf and V f value results represent<br />

the tectonic activity class 1. Nevertheless, according to the morphometric analysis results<br />

the southern region is being slightly less tectonically active than the northern region.<br />

167


Furthermore, the valley profile shapes in the southern region demonstrate a higher<br />

number of U-shaped compared to V-shaped profiles, which may also be partly<br />

attributable to the presence of the largely sandstone and less granite mountains in the<br />

southern area compared to the predominantly limestone in the Dead Sea and northern<br />

Araba areas (Bender 1974a, 1974b, 1975, 1982, Burdon 1959).<br />

Another factor that might have a minimal impact on the alteration of the valley<br />

shapes is the seasonal flash floods in southern Jordan. As a matter of fact, continuing<br />

flash floods in the dry to semi-arid climates, similar to Jordan, drive the primary incisions<br />

incidents that result in extensive erosion in mountain fronts and valleys based on the<br />

difference in their rock resistance (de Jaeger and de Dapper 2002). Practically, in the<br />

absence of tectonic activity, the weathering and erosion processes have a significant<br />

impact on all rocks regardless of their type and resistance. Thus, not only the tectonic<br />

activity of the region has contributed to the alteration of valley shapes which in turn have<br />

a direct effect of the V f values, but the geology of the area has also played an additional<br />

role due to the presence of relatively soft rock type mountains.<br />

4.3. Seismic activity at mountain fronts<br />

Although, the combined data from all tectonic morphometric index analyses<br />

highlight significant variations in relative and numerical values of the JDTZ tectonic<br />

activity; it is very substantial to integrate current field and historical seismological data in<br />

order to examine the position of recorded earthquakes relative to mountain fronts, and<br />

variations in rocks and weathering processes that have their input to the variations of the<br />

overall calculations (Wells et al. 1988).<br />

168


According to Allen (1975), major earthquakes with high magnitudes have<br />

occurred along faults that are correlated to active mountain fronts. The major earthquake<br />

events in the study area have taken place within or in close proximity to the active<br />

seismic zones that are characterized by several active faults. These events were primarily<br />

distributed along and at the intersections of the major active faults in the JDTZ that<br />

comprises the Dead Sea area in the north, the Aqaba area in the south, and Wadi Araba<br />

region. To better illustrate the distribution of earthquake events in the JDTZ, a tectonic<br />

map has been generated utilizing all available historic and recent earthquake events<br />

recorded in Jordan demonstrating the earthquakes network and mountain fronts<br />

relationship, as shown in figure 4.3.<br />

It is obvious that the recorded earthquake events occurred in the northern and<br />

southern regions of the JDTZ are concentrated within the active tectonic zones. In<br />

addition, the tectonic events occurred close to the examined mountain fronts, which are<br />

also adjacent to the active Dead Sea-Jordan River (zone 1) and the northern part of the<br />

Wadi Araba fault lines (zone 3) indicate that this region has experienced larger<br />

magnitude tectonic activity. On the contrary, frequent small magnitude earthquakes<br />

occurred in the southern region nearby the examined mountain fronts in the southern part<br />

of the Wadi Araba fault line (zone 3), whereas the large number of events occurred<br />

further south in the vicinity of the main fault line of the northern Red Sea and the Gulf of<br />

Aqaba (zone 5), as illustrated in figures 4.3 and 4.4.<br />

169


Figure 4.3: Network of earthquakes-mountain fronts’ relationship on the JDTZ showing<br />

earthquake events of M L 4 to 6 and tectonic zones, 19A.D. to August 1983.<br />

170


Figure 4.4: Network of earthquakes-mountain fronts’ relationship on the JDTZ showing<br />

earthquake events of M L 4 to 6 and tectonic zones, September 1983 to 2005.<br />

171


4.4. The accuracy of ASTER DEM data<br />

Elevation is one of the most important datasets in many natural resource and<br />

geomorphological spatial databases that is often used for DEM construction. The<br />

accuracy of these DEMs and their derived products are of critical significance because<br />

errors in the base data will propagate through morphometric and spatial analyses. This is<br />

principally correct where elevation is derived from DEMs and used with other spatial<br />

data. Therefore, errors in elevation will often cause errors in the generated model outputs<br />

(Bolstad and Stowe 1994, Kamp et al. 2003, 2005).<br />

ASTER sensors provide images with a scale of 1:50,000 (Hirano et al. 2003, Lang<br />

and Welch 1999, Lang et al. 1996, Poli et al. 2005, Toutin and Cheng 2001). Moreover,<br />

the along-track stereo data acquisition eliminates the radiometric variations caused by<br />

multi-date stereo data acquisition, which compensate for the weaker stereo geometry and<br />

ultimately improves the image matching performance. It is possible to produce stereo-<br />

DEMs with excellent accuracy when using ground control points (GCPs) measure with<br />

high precision methods. The GCPs are features that could be clearly identified in the<br />

satellite image which have a known ground coordinate. The relationship between the raw<br />

satellite image and GCPs are determined by associating the pixels in the image to the x,<br />

y, and z coordinated system on the ground (figure 4.5). The main source for the<br />

horizontal and vertical values of such check points come from variety of sources such as<br />

GPS, ground surveys, existing topographic maps, and geocoded images (Chrysoulakis et<br />

al. 2004, Cuartero et al. 2004, Fujisada et al. 2001, Poli et al. 2005, Toutin and Cheng<br />

2001). This is widely used in cloud-free images in arid to semi-arid regions where the<br />

elevation accuracy could reach up to 10m (Fujisada et al. 2001, Toutin and Cheng 2001).<br />

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Figure 4.5: The relationship between the ground and the image coordinate systems<br />

(Geomatica 2003, figure 5.1, p. 33).<br />

Nevertheless, a significant feature of the ASTER stereo system concept is to<br />

generate high quality DEM data without referring to GCPs for individual scenes<br />

depending on the spacecraft ephemeris and the instrument parameters (Fujisada et al.<br />

2001, Kamp et al. 2003, 2005). Therefore, relative DEM is defined as elevation data<br />

generated by not using GCPs, and derived from ASTER stereo pair image using stereo<br />

matching method. On the other hand, absolute DEM requires referencing to a map<br />

coordinate system using GCPs of know locations on the ground to enhance the elevation<br />

data generated from ASTER stereo pair image (Lang and Welch 1999, Tokunaga et al.<br />

1996). Normally, ASTER DEMs with relative accuracy can be used productively to assist<br />

mapping, geomorphic, geologic, tectonic, landform, and a range of environmental studies<br />

in remote areas of rugged terrain (Hirano et al. 2003, Lang and Welch 1999).<br />

ASTER is a relatively recent sensor and there is little research focusing it its DEM<br />

accuracy. In fact, most researches that analyses the accuracy of DEM generated were<br />

173


performed mainly on simulated ASTER data (Abrams and Hook 1995, Lang and Welch<br />

1999, Welch et al. 1998, Cuartero et al. 2004). However, Lang and Welch (1999) suggest<br />

that the root mean square error (RMSE) for elevation values in ASTER DEM should be<br />

in the range of ±10m to ±50m, which is a broad range to define the accuracy of a product,<br />

other researches suggest a DEM elevation accuracy of less than one pixel size (15m) and<br />

up to ±7m (Cuartero et al. 2004, Hirano et al. 2003), where normally the RMSE values<br />

are on the order of ±7m to ±30m (Kamp et al. 2005). Commonly, a DEM created from<br />

ASTER imagery can be expected to have a vertical accuracy of about ±25m. However, in<br />

areas with less vegetation or man-made features, the accuracy can rise to approximately<br />

±10m. Such DEMs are generated with scales of 1:50,000 to 1:100,000 that are useful for<br />

small to medium scale mapping applications and the interpretation of macro- and<br />

mesorelief in areas where high-accuracy commercial DEMs data products are not<br />

available (Kamp et al. 2003, Selby 2003).<br />

ASTER DEMs which were created using GCPs typically produce absolute<br />

elevations (Chrysoulakis et al. 2004) and fully scaled and precision located DEMs and<br />

orthoimages (Selby 2003). In general, the elevation error when using high accuracy GCPs<br />

is less than 15m (Fujisada et al. 2001). Assuming the parallax difference in the range of<br />

0.5 to 1.0 pixels (i.e. 7-15m), the root mean square error (RMSE) of the elevation error is<br />

expected to be in the ±12m to ±26m range. The planimetric and elevation accuracy of the<br />

ASTER produced DEM were found to be ±15m and ±12.4m, respectively, and<br />

considered quite satisfactory for large study areas (Chrysoulakis et al. 2004). According<br />

to previous studies on ASTER derived DEMs, the vertical accuracy is approximately<br />

between ±7 to ±15m and horizontal accuracy of about one pixel with a mean values<br />

174


smaller than one pixel, while the RMSE and standard deviation are slightly larger than<br />

one pixel size (Cuartero et al. 2004, Hirano et al. 2003, Poli et al. 2005).<br />

Based on the study conducted by Hirano et al. (2003), the evaluations of ASTER<br />

DEMs vertical accuracy created by automatic stereo correlation method using PCI<br />

OrthoEngine indicate that an approximate RMSE for z-values of ±7m to ±15m and up to<br />

±10m, where occasionally ±8.6m can be expected when using good quality and adequate<br />

tie pints or GCPs (Hirano et al. 2003).<br />

4.5. ASTER DEM error test<br />

The extraction of topographic information from generated DEMs is becoming a<br />

common method in geomorphic analysis and surface modeling processes. Therefore, it is<br />

essential to generate a DEM with great precision that is able to represent the terrain as<br />

accurately as possible, which eventually will determine the reliability of the<br />

morphometric analysis results (Kamp et al. 2003).<br />

In the case of DEMs, the errors are of attributive type implying an incorrect<br />

assignment of altitude and they modify the z-values. These errors commonly appear in<br />

the creation process of DEMs, both by automatic and manual procedures. The automatic<br />

errors are generated mainly by automatic stereo correlation methods that may have<br />

operative problems as a result of low contrasts in images, ambiguities due to the<br />

repetition of objects of periodic patterns (Felicísimo 1994). Previous researches (Cuartero<br />

et al. 2004, Hirano et al. 2003, Poli et al. 2005) have pointed out that the vertical accuracy<br />

(i.e. elevation) of the ASTER generated DEMs in areas of less vegetation could be on the<br />

order of ±7m to ±30m and can roughly reach ±10m. As an example, if the elevation in a<br />

given location is 1000m in the generated ASTER DEM, this means that the elevation<br />

175


could either be 990m or 1010m. Therefore, the ASTER derived DEMs will definitely<br />

have a direct impact on the overall results of the tectonic geomorphic analysis of the<br />

mountain fronts and valleys used in the research.<br />

In most articles, critical analyses on the error sources using GIS application are<br />

noticeably absent, and that derived products are presented without any estimate of their<br />

accuracy (Felicísimo 1994). Although, testing the accuracy of ASTER elevations is<br />

beyond the scope of this research; using variance-covariance error propagation to<br />

calculate uncertainties (or errors) and the variance values will shed the light on the<br />

accuracy of the calculated tectonic geomorphic indices results in terms of vertical<br />

elevation accuracy and suitability to the actual study area elevation. This means,<br />

evaluating the generated DEMs quality and measuring their reliability in providing the<br />

needed results to serve the purpose of the research.<br />

Error propagation techniques are used to evaluate the resulting errors (e.g.<br />

standard deviation) in quantities that are calculated from a set of measurements (Mikhail<br />

and Gracie 1977, Taylor 1997). This method of computing the magnitudes of errors in<br />

measurements are based upon the assumption that the measurement errors are already<br />

known and given. Practically, if the errors are know they could be simply eliminated by<br />

applying accurate corrections leaving nothing to propagate. Alternatively, if random<br />

errors were considered, even though the specific values of the random errors are not<br />

know, studying the effect of their effect is still possible. In this case, the probability<br />

distributions of the errors are used instead of dealing with the actual error values, or,<br />

equally, working with the probability distributions of the corresponding measurements<br />

and calculated quantities. Therefore, if the set of measurements are represented by the<br />

176


andom factor x, and the calculated quantities are represented by the random vector y<br />

such that y = f ( x)<br />

, then the propagation involves finding the combined probability<br />

distribution of y by specifying the joint probability distribution of x. This can be<br />

accomplished by limiting the consideration to a linear function of x or to linearized forms<br />

of nonlinear functions of x simply by employing the propagation of variances and<br />

covariances (Mikhail and Gracie 1977).<br />

Since variances and covariances are expectations, therefore calculating the<br />

variance-covariance propagation is best accomplished using the approach of defining<br />

variances and covariances in terms of sums calculated from samples of infinite size, in<br />

our case of only four variables (Mikhail and Gracie 1977). Consider a dependent variable<br />

(i.e. random variable) y as a linear combination of an independent variable x that consists<br />

of four variables namely V fw , E ld , E rd , and E sc representing the acquired vertical<br />

(elevations) and horizontal (valley floor width) measurements of the V f index equation<br />

expressed in a linear regression equation such that:<br />

y = Ax + b<br />

In which A is a 4 x 4 coefficient matrix, and the b is the regression coefficient constant<br />

(Mayer 1990, Mikhail and Gracie 1977). Simply, the y value equals the sum of the<br />

constant b that represents the point, at which the line intercepts the y-axis, plus the<br />

product of the slope x times the A value. Similarly, the line’s y intercepts b demonstrates<br />

the y value when A = 0. The line’s slope x shows the amount of change in y units for oneunit<br />

change in A (Knoke et al. 2002, Pipes and Harvill 1970). So, the previous equation is<br />

written more formally given a functional relationship between several measured variables<br />

as:<br />

177


y = Vfwx + Eld x + Erd x + Escx + b<br />

If the deviation of the calculated values of y from its mean value µ y is:<br />

∆ y = y − µ y<br />

It can be show that:<br />

∆ y = V<br />

fw∆ x + Eld ∆ x + Erd∆ x + Esc∆<br />

x<br />

Defining the variances and covariances of y in terms of the existing four random<br />

variables q representing V fw , E ld , E rd , E sc by applying the ith sample component such as:<br />

σ<br />

1<br />

q<br />

2 2<br />

y<br />

= lim ∑ ∆yi<br />

q→∞<br />

q i=<br />

1<br />

The variation in dV f as a function of the uncertainties in V fw , E ld , E rd , and E sc can<br />

be derived by taking the partial derivative of the V f index equation (Pipes and Harvill<br />

1970, Ruffhead 1998, Skoog and Leary 1992, Taylor 1997). Partial derivative of a<br />

function of multiple variables involves the derivative with respect to one of those<br />

variables with the others held constant, that is:<br />

2 Vfw<br />

V<br />

f<br />

=<br />

[(E - E ) + (E - E )]<br />

ld sc rd sc<br />

⎡ 2 ⎤ ⎡ ∂V<br />

fw ⎤ ⎡ ∂V<br />

fw ⎤<br />

dV<br />

f<br />

= ⎢ ⎥ dV<br />

fw<br />

+ ⎢ ⎥ dEld + ⎢ ⎥ dErd<br />

+<br />

⎣(E ld<br />

- E<br />

sc<br />

) + (E<br />

rd<br />

- E<br />

sc<br />

) ⎦ ⎣( ∂Eld<br />

) ⎦ ⎣( ∂Erd<br />

) ⎦<br />

⎡ ∂V<br />

fw ⎤<br />

⎢ ⎥ dE<br />

⎣( ∂Esc<br />

) ⎦<br />

sc<br />

⎡ 2 ⎤ ⎡ −2V<br />

fw ⎤<br />

dV<br />

f<br />

= ⎢ ⎥ dVfw + ⎢ 2 ⎥ dEld<br />

+<br />

⎣(E ld<br />

- E<br />

sc<br />

) + (E<br />

rd<br />

- E<br />

sc<br />

) ⎦ ⎣(E ld<br />

- E<br />

sc) + (E<br />

rd<br />

- E<br />

sc)<br />

⎦<br />

⎡ −2V<br />

fw ⎤ ⎡ 4V<br />

fw ⎤<br />

⎢ 2 ⎥ dEld<br />

+ ⎢ 2 ⎥ dE<br />

⎣(E ld<br />

- E<br />

sc) + (E<br />

rd<br />

- E<br />

sc<br />

) ⎦ ⎣(E ld<br />

- E<br />

sc) + (E<br />

rd<br />

- E<br />

sc)<br />

⎦<br />

sc<br />

178


Consequently, to develop a relationship between the standard deviation and the V f<br />

and the standard deviations of V fw , E ld , E rd , and E sc it is necessary to square the previous<br />

equation (this equation is true if there is no correlation), thus the linear function is<br />

presented as:<br />

σ = a σ + b σ + c σ + d σ<br />

2 2 2 2 2 2 2 2 2<br />

Vf Vf Eldf Erd Esc<br />

Generally, it is more convenient to express the regression equations in matrix<br />

form (Mayer 1990), considering the covariance matrix of the random four variables as:<br />

S<br />

xx<br />

2 2 2 2<br />

⎡σVfw σ<br />

Eld<br />

σ<br />

Erd<br />

σ ⎤<br />

Esc<br />

⎢ 2 2 2 2 ⎥<br />

σ<br />

Eld<br />

σ<br />

Eld<br />

σ<br />

EldErd<br />

σ<br />

EldEsc<br />

= ⎢<br />

⎥<br />

⎢<br />

2 2 2 2<br />

σ<br />

Erd<br />

σ<br />

EldErd<br />

σ<br />

Erd<br />

σ<br />

ErdEsc ⎥<br />

⎢<br />

2 2 2 2<br />

⎥<br />

⎢⎣<br />

σ<br />

Esc<br />

σ<br />

EldEsc<br />

σ<br />

ErdEsc<br />

σ<br />

Esc ⎥⎦<br />

2<br />

The preceding equation can be easily expressed in the matrix form where σ<br />

Vf<br />

is<br />

the variance of V f such that:<br />

σ = AS A'<br />

2<br />

Vf<br />

xx<br />

where A is the coefficient matrix and<br />

A ' is the coefficient matrix transpose (Mayer 1990,<br />

Mikhail and Gracie 1977). Substituting the coefficient matrix A into the foregoing<br />

equation yields (this equation is true if there is correlation):<br />

σ<br />

2<br />

Vf<br />

=<br />

[ a b c d ][ S ]<br />

xx<br />

⎡a⎤<br />

⎢<br />

b<br />

⎥<br />

⎢ ⎥<br />

⎢c<br />

⎥<br />

⎢ ⎥<br />

⎣d<br />

⎦<br />

This result in:<br />

179


σ<br />

2<br />

Vf<br />

=<br />

[ a b c d ]<br />

⎡σ σ σ σ<br />

⎢<br />

⎢σ σ σ σ<br />

⎢σ σ σ σ<br />

⎢<br />

⎢⎣<br />

σ σ σ σ<br />

2 2 2 2<br />

Vfw Eld Erd Esc<br />

2 2 2 2<br />

Eld Eld EldErd EldEsc<br />

2 2 2 2<br />

Erd EldErd Erd ErdEsc<br />

2 2 2 2<br />

Esc EldEsc ErdEsc Esc<br />

⎤ ⎡a⎤<br />

⎥ ⎢<br />

b<br />

⎥<br />

⎥ ⎢ ⎥<br />

⎥ ⎢c<br />

⎥<br />

⎥ ⎢ ⎥<br />

⎥⎦<br />

⎣d<br />

⎦<br />

All elevation values for the independent variables E ld , E rd , and E sc were obtained<br />

using the same DEM to calculate valley profile values (V f ) in each satellite scene of the<br />

JDTZ. Presuming no fluctuation in the acquired elevation values of these independent<br />

variables, logically, any error in the DEM will affect all calculated measurements, and as<br />

a result the correlation value of these variables will be very high. Therefore, when the<br />

components of the random variables are independent, the covariance matrix<br />

Sxx<br />

is<br />

diagonal (Mikhail and Gracie 1977). Ideally, the observed errors are obtained by<br />

collecting control points using GPS and compare it to the generated DEM to create an<br />

absolute DEM. Nevertheless, since the assumed ASTER vertical elevation error is ±10m<br />

(i.e. E ld , E rd , E sc ), and the ASTER generated DEMs horizontal accuracy (i.e. pixel size,<br />

2<br />

V fw ) might shift in the order of half a pixel (30m/2 = 15m), thus, the V f variance σ<br />

Vf<br />

is<br />

2<br />

equal to σ (10m 2 = 100) and<br />

Eld , Erd , Esc<br />

matrix is expressed as follow:<br />

2<br />

σ<br />

Vfw<br />

(15m 2 = 225), respectively, and the covariance<br />

S xx<br />

⎡225 0 0 0 ⎤<br />

⎢<br />

0 100 95 95<br />

⎥<br />

= ⎢<br />

⎥<br />

⎢ 0 95 100 95 ⎥<br />

⎢<br />

⎥<br />

⎣ 0 95 95 100⎦<br />

Assuming the correlation between the independent variables E ld , E rd , and E sc is<br />

0.95 (Cor Eld, Erd, Esc = ρ = 0.95). Therefore, the covariance of the elevation of the<br />

independent variables is expressed as:<br />

180


( σ<br />

ei<br />

)<br />

ej<br />

ρ = where i = 1,2,3 and j = 1,2,3<br />

( σ xσ )<br />

eiej<br />

ei<br />

ej<br />

σ = ρ σ xσ )<br />

(<br />

ei ej<br />

σ<br />

eiej<br />

= 0 .95(10x10)<br />

= 95<br />

Thus, after substituting this value the final integrated equation is expressed as:<br />

σ<br />

2<br />

Vf<br />

=<br />

[ a b c d ]<br />

⎡σ<br />

⎢<br />

⎢<br />

⎢<br />

⎢<br />

⎢⎣<br />

0 0 0<br />

2<br />

Vfw<br />

0<br />

2<br />

σ<br />

Eld<br />

95 95<br />

0 95<br />

2<br />

σ<br />

Erd<br />

95<br />

2<br />

0 95 95 σ<br />

Esc<br />

⎤ ⎡a⎤<br />

⎥ ⎢<br />

b<br />

⎥<br />

⎥ ⎢ ⎥<br />

⎥ ⎢c<br />

⎥<br />

⎥ ⎢ ⎥<br />

⎥⎦<br />

⎣d<br />

⎦<br />

This result in the following equation after substituting the covariance matrix values:<br />

σ<br />

2<br />

Vf<br />

=<br />

[ a b c d ]<br />

⎡225 0 0 0 ⎤ ⎡a⎤<br />

⎢<br />

0 100 95 95<br />

⎥ ⎢<br />

b<br />

⎥<br />

⎢<br />

⎥ ⎢ ⎥<br />

⎢ 0 95 100 95 ⎥ ⎢c<br />

⎥<br />

⎢<br />

⎥ ⎢ ⎥<br />

⎣ 0 95 95 100⎦ ⎣d<br />

⎦<br />

To calculate the uncertainty<br />

σ<br />

Vf<br />

values (the deviation from the mean) for each<br />

individual valley profile, the square root (SQR, square terms are always positive) must be<br />

2<br />

calculated for the V f variance values σ<br />

Vf<br />

to obtain the standard deviation σ<br />

Vf<br />

values of all<br />

valley profiles. Finally, the<br />

σ<br />

Vf<br />

values will be added to and subtracted out of the V f index<br />

values of each valley profiles to determine the effect of the assumed ASTER elevation<br />

errors on the final results and in turn establish the finals active tectonic classes and their<br />

ranges.<br />

To perform the variance-covariance error propagation analysis, MATLAB 7.0<br />

software has been employed for this purpose using the previously calculated V f results.<br />

The MATLAB command lines listed in table 4.3 explains the step-by-step procedures to<br />

181


obtain the standard deviation (i.e. σ Vf ) and the variance results of each valley profile. The<br />

MATLAB commands are color-coded whereas each set of commands are highlighted, the<br />

main command lines are black and preceded with (-) sign, instructions in green explain<br />

the MATLAB command, and instructions in red explain commands procedures where<br />

Vdata = the partial derivative calculations of ABCD (new output data), Obsdata = the V f<br />

calculations (input or observation data), Sxx = the covariance matrix, Syy = the<br />

covariance matrix of all profile ratios, Std = the standard deviation values, Columns 1 and<br />

2 = the fronts and valley profiles numbers, respectively, Columns 3 to 6 = the A, B, C,<br />

and D calculation values, respectively, Column 7 = the ABCD * Sxx * ABCD'<br />

calculation results, Column 8 = the SQR (results of the final dV f equation), and Column 9<br />

= the V f mean values for each valley profiles set related to a mountain front.<br />

Tables 4.4 to 4.7 illustrate the final V f tectonic classes and the σ Vf values that<br />

represent the final results of the ASTER accuracy equation. In addition, the final<br />

+ ) and ( V<br />

f<br />

− σ ) results for all regions within the study area are listed<br />

Vf<br />

( V<br />

f<br />

σ<br />

Vf<br />

considering the vertical accuracy ±10m and the horizontal pixel size 30m of the ASTER<br />

derived DEMs (figure 4.6). The lowest and highest final values of 0.02 and 2.25 were<br />

found in Aqaba and the Dead Sea area, respectively. Since the V f index is a ratio and its<br />

analysis normally expressed as absolute values (in this case as positive numbers),<br />

therefore, all negative values after subtracting the DEM accuracy results (σ Vf ) out of the<br />

V f values ( V<br />

f<br />

− σ ) were out of range (i.e. equal zero) and considered as class 1<br />

Vf<br />

throughout the final V f tectonic activity class classification. The presence of negative<br />

values is donated to the shallowness of the valley bottom creating small differences in the<br />

elevations of the valleys divides compared to the valley floors. This has only occurred in<br />

182


a small number of valley profiles within the JDTZ (Dead Sea = 6 profiles, North Araba =<br />

1 profile, South Araba = 4 profiles, and Aqaba = 2 profiles).<br />

01<br />

02 %% Clear data (erases previous calculations)<br />

03<br />

04 -<br />

clear abcd i vdata Sxx (abcd = partial derivative results, vdata = outputs,<br />

and Sxx = covariance matrix)<br />

05<br />

06 %% Read xls file (reading data from an Excel file)<br />

07<br />

08<br />

%reads abcd values for a single front (specify new valley by changing the range values<br />

and spreadsheet number, e.g. sheet #3 )<br />

09 - vdata = xlsread (All_Calculations' , 3, 'S180 : X187');<br />

10<br />

11 %reads observation covariance matrix (same for all valleys)<br />

12 - Sxx = xlsread (All_Calculations' , 3, 'AC13 : AF16');<br />

13<br />

14 %raw observatoins and vf calculations (different range for each valley profile data)<br />

15 - obsdata = xlsread ('All_Calculations' , 3, 'B180 : J187');<br />

16<br />

17 % covariance matrix of all profile ratios<br />

18 - Syy = abcd * Sxx * abcd’;<br />

19<br />

20 %% compute variance of each profile (numbers indicate the output table columns)<br />

21 - abcd = vdata (:, 3, 6);<br />

22 - vdata (:, 7) = diag (abcd * Sxx * abcd’);<br />

23 - vdata (:, 8) = sqrt (vdata (:, 7));<br />

24<br />

25 %% compute mean of a front<br />

26 - V f _mean = mean (obsdata (:, 9));<br />

27<br />

28 %% compute standard deviation of a front<br />

29 - V f _std = sqrt (V f _var);<br />

30 - V f _std_excel = std (obsdata (:, 9));<br />

31<br />

32 %% compute variance (V f _var) of a front assuming correlations among profiles<br />

33 - V f _var = ((obsdata (:, 9)’ – V f _mean) * Syy * (obsdata (:, 9) – V f _mean))/<br />

34 (nume1 (obsdata (:, 9)) – 1);<br />

35<br />

36 %% Draw histogram of V f (creates a histogram of each valley profile)<br />

37 - hist (obsdata (:, 9));<br />

38 - axis ([0 2 0 10])<br />

39 - grid on<br />

40<br />

41 %% Write new data to a new spreadsheet (creates a new sheet and writes the new data)<br />

42<br />

43 %xlswrite (vdata,' spreadsheet-name' , 'sheet#' , 'range ## : ##');<br />

44<br />

Table 4.3: MATLAB command lines (each set of commands are highlighted, command<br />

lines are black and start with (-), instructions in green explain the MATLAB commands,<br />

and instructions in red explain commands procedures).<br />

183


184


185


186


187


188


Figure 4.6: The tectonic activity classes of all S mf and V f based on V f +σ Vf results.<br />

189


In table 4.8, the percentages of the valleys tectonic activity classes of the study<br />

area are presented subsequent to employing the ASTER DEM error calculation results<br />

(i.e. ±σ Vf values). In all four regions of the JDTZ, a significant increase (higher<br />

percentages) of the final results are illustrated after adding the final V f accuracy test<br />

values (i.e. ±σ Vf ) to the previously calculated V f values of each individual valley profile<br />

compared to lower values (decreased percentages) when perform substituting. This<br />

indicates the importance of using both addition and subtracting values of the DEM<br />

accuracy test to determine the final tectonic activity classes in these four regions. Thus,<br />

the minimum and maximum values of this accuracy test will establish the range of the V f<br />

final tectonic classes within the JDTZ study area.<br />

4.6. Final results and tectonic activity classes<br />

Generally, the S mf results in the northern area show lower values compared to the<br />

southern area which indicates a slightly more tectonic activity in this part of the JDTZ<br />

region. However, the V f values in the northern area demonstrate a higher values in<br />

comparison with the southern area, which is primarily related to the difference in the<br />

geological setting and rock types between the two regions. The southern area, on the<br />

other hand, has more U-shaped valleys as a result of relative tectonic quiescence<br />

compared to the northern area that has largely V-shaped valleys indicating more tectonic<br />

activity. These tectonic activity results match the recorded field and historical seismic<br />

data of the region as previously illustrated in the earthquake network and active faults<br />

relationship maps (section 4.3, figures 4.3 and 4.4).<br />

190


Dead Sea (22 valleys)<br />

Class change Initial class to New class Percentage of valleys<br />

1-2 → 1 5 / 22 = 22.7%<br />

Decreased<br />

2 → 1 or (1-2) 4 / 22 = 18.2%<br />

Not changed (decreased) 13 / 22 = 59.1%<br />

Total decreased 40.9%<br />

1 → 2 or (1-2) 8 / 22 = 36.4%<br />

1-2 → 2 or 3 4 / 22 = 18.1%<br />

Increased 2 → 3 2 / 22 = 9.10%<br />

Not changed (increased) 8 / 22 = 36.4%<br />

Total increased 63.6%<br />

Not changed (increased or decreased) 5 / 22 = 22.7%<br />

North Araba (15 valleys)<br />

Class change Initial class to New class Percentage of valleys<br />

1-2 → 1 6 / 15 = 40.0%<br />

Decreased<br />

2 → 1 or (1-2) 1 / 15 = 6.70%<br />

Not changed (decreased) 8 / 15 = 35.3%<br />

Total decreased 46.7%<br />

1 → 2 or (1-2) 6 / 15 = 40.0%<br />

1-2 → 2 or 3 4 / 15 = 26.7%<br />

Increased 2 → 3 0 / 15 = 0.00%<br />

Not changed (increased) 5 / 15 = 33.3%<br />

Total increased 66.7%<br />

Not changed (increased or decreased) 2 / 15 = 13.4%<br />

South Araba (25 valleys)<br />

Class change Initial class to New class Percentage of valleys<br />

1-2 → 1 3 / 25 = 12.0%<br />

Decreased<br />

2 → 1 or (1-2) 3 / 25 = 12.0%<br />

Not changed (decreased) 19 / 25 = 76.0%<br />

Total decreased 24.0%<br />

1 → 2 or (1-2) 5 / 25 = 20.0%<br />

1-2 → 2 or 3 4 / 25 = 16.0%<br />

Increased 2 → 3 0 / 25 = 0.00%<br />

Not changed (increased) 16 / 25 = 64.0%<br />

Total increased 36.0%<br />

Not changed (increased or decreased) 12 / 25 = 48.0%<br />

Aqaba (36 valleys)<br />

Class change Initial class to New class Percentage of valleys<br />

1-2 → 1 2 / 36 = 5.60%<br />

Decreased<br />

2 → 1 or (1-2) 0 / 36 = 0.00%<br />

Not changed (decreased) 34 / 36 = 94.4%<br />

Total decreased 5.60%<br />

1 → 2 or (1-2) 2 / 36 = 5.60%<br />

1-2 → 2 or 3 1 / 36 = 2.80%<br />

Increased 2 → 3 0 / 36 = 0.00%<br />

Not changed (increased) 33 / 36 = 91.6%<br />

Total increased 8.40%<br />

Not changed (increased or decreased) 31 / 36 = 86.2%<br />

Table 4.8: Percentages change of all valleys tectonic classes after applying the ±σ Vf<br />

values.<br />

191


The final morphometric analysis of the S mf and V f indices revealed that the JDTZ<br />

is tectonically active with slightly more activity in its northern part (figure 4.7). Theses<br />

results uphold the historic and recorded earthquake data of the region where the northern<br />

part of the JDTZ has experienced more noticeable tectonic activities than its southern<br />

part. Based on the available digital data, the S mf and V f results indicate that there are two<br />

main tectonic activity classes: more active (class 1), and moderate to less active (class 2).<br />

The active class 1 S mf result ranges from 1.00 to 1.30, whereas class 2 values are > 1.30.<br />

The V f results show the possibility of having an additional less active (or inactive)<br />

tectonic class (class 3) that is still considered as a component of the moderate to less<br />

active class 2. The V f active class 1 ranges from ≤ 0.09 to 0.50, the moderate to less<br />

active class 2 ranges from 0.51 to 1.88, and the less active to inactive class 3 values are ><br />

1.88 (table 4.9).<br />

Tectonic activity classes and description S mf V f<br />

Class 1 More active 1.00 – 1.30 ≤ 0.09 – 0.50<br />

Class 2 Moderate to Less Active > 1.30 0.51 – 1.88<br />

Class 3 Less Active (inactive) - > 1.88<br />

Table 4.9: Final S mf and V f tectonic activity classes.<br />

Similar to any other digital data, the generated DEMs primarily depend on the<br />

resolution of the satellite imagery source. Thus, the better the initial ASTER imagery<br />

resolution, the more enhanced DEMs quality could be created, hence, extra accurate<br />

calculations of both S mf and V f indices. The values of S mf and V f indices analysis in the<br />

JDTZ are reasonably close to the morphometric analysis results reached by other<br />

researchers (chapter 2, table 2.1). These tectonic indices results were based on the<br />

proposed ASTER vertical accuracy of ±10m and the generated DEMs horizontal pixel<br />

size of 30m. This indicates the morphometric analysis of S mf and V f using the digital<br />

192


approach has great potential in determining the tectonic activity classes in the JDTZ<br />

study area.<br />

Figure 4.7: The active tectonic classes of the northern and southern regions of the JDTZ<br />

showing all S mf and V f +σ Vf results.<br />

193


5. Chapter Five: Conclusion<br />

5.1. Conclusion<br />

The mountain front sinuosity index (S mf ) and the ratio of valley floor width to<br />

valley height (V f ) are useful indicators of relative tectonic activity. Nevertheless, utilizing<br />

the new digital approach as presented in this research, based on satellite imagery and<br />

geographic digital data of land features, requires thorough examination and additional<br />

research. Generally, remote sensing has limitations, and to get accurate geomorphic<br />

analysis results it would be highly recommended if carried out together with ground<br />

truthing (i.e. ground referencing data) and obtaining precise GPS elevation data of the<br />

JDTZ study area.<br />

The relative 30m-DEMs of the JDTZ were successfully generated from ASTER<br />

imagery using PCI OrthoEngine software. ASTER digital data are available for many<br />

parts of the Earth for a reasonable purchase price of US $55 per scene. ASTER imagery<br />

and the derived DEMs provide good sources for mapping at scales in the range of<br />

1:100,000 and 1:50,000 and for obtaining relative details about topography and elevation<br />

information for a wide range of terrains (Kamp et al. 2003).<br />

The morphometric analysis of mountain front sinuosity and the ratio of valley<br />

floor width to valley height have proven to be useful in determining the tectonic activity<br />

of several regions of different geological settings (Chapter two, section 2.3). The results<br />

of the digital morphometric analysis approach of the S mf and V f indices in the JDTZ are<br />

consistent with the northern area been of somewhat more tectonically active than the<br />

southern area. Based on the available digital data, the S mf and V f results indicate that<br />

there are two main tectonic activity classes: more active (class 1), and moderate to less<br />

194


active (class 2). The active class 1 sinuosities (S mf ) result ranges from 1.00 to 1.30,<br />

whereas class 2 values are > 1.30. The V f index results illustrate the possibility of having<br />

an additional less active (inactive) tectonic class (class 3), but it is still considered as a<br />

component of the moderate to less active tectonic category as in class 2. The V f active<br />

class 1 ranges from ≤ 0.09 to 0.50, the moderate to less active class 2 ranges from 0.51 to<br />

1.88, and the less active class 3 values are > 1.88.<br />

Although the new digital approach has only been tested in Jordan on an arid to<br />

semi arid region, it has the potential of providing reliable results for morphometric<br />

analysis and quantifying the tectonic activity in the JDTZ study area. Indeed, further<br />

studies using the new approach are highly recommended in different places and terrains<br />

of different geological settings to examine this method’s efficiency.<br />

However, the combined data from all analysis of morphometric landscape<br />

parameters highlight significant variations in relative and numerical values of the JDTZ<br />

tectonic activity. It is critical to integrate field data in order to examine other nontectonic<br />

factors such as drainage basin size, stream power, position of fluvial systems relative to<br />

mountain fronts, and variations in bedrock and weathering processes that have their input<br />

to the variations of the overall calculations (Wells et al. 1988).<br />

In conclusion, with the available ASTER satellite imagery and the resolution of<br />

the ASTER derived DEM (30m pixel size and ±10m vertical accuracy), the digital<br />

morphometric analysis approach of mountain fronts (S mf ) and valley profiles (V f ) has the<br />

potential of providing results that are useful in determining the tectonic activity of the<br />

JDTZ study area. More accurate and reliable results could be obtained utilizing the digital<br />

195


S mf and V f indices analysis with the use of smaller DEM ground resolution of 15m to<br />

10m or less.<br />

5.2. Limitation of the Study<br />

Since this research is believed to be among the first attempts to use a digital<br />

geomorphic analysis approach for calculation of morphometric indices, the literature<br />

discussing this method was scarce and quite limited. In addition, ASTER imagery data<br />

has never been used in any previous research in Jordan, thus, the accuracy of the obtained<br />

ASTER digital data have never been tested against the various existing terrains in Jordan<br />

and the JDTZ.<br />

One of the major inadequacies in this research that would have added valuable<br />

information is the lack of digital data and comprehensive tectonic databases of Jordan.<br />

Furthermore, the absence of the large scale topographic maps (1:25,000 or larger) of the<br />

JDTZ study area hindered their comparison with the ASTER derived DEMs to perform<br />

DEM accuracy test by using a simple map algebra operator (Cuartero et al. 2004). In<br />

addition, there is a lack of ground control points (GCPs) and other elevation data such as<br />

that can be obtained by the use of differential global positioning system (GPS) method<br />

within the JDTZ study area (Chrysoulakis et al. 2004, Leick 2004, Poli et al. 2005).<br />

5.3. Future directions/remarks<br />

It has been studied that various indices have different sensitivities to specific<br />

types and rates of tectonic activity, in addition to variables such as lithology, alluvial<br />

fans, and drainage basin size (Wells et al. 1988). Moreover, both mountain front sinuosity<br />

(S mf ) and stream length-gradient index (SL) are potentially valuable reconnaissance tools<br />

used to identify areas of relative tectonic activity when jointly exploited. As a result, this<br />

196


study stresses the value of incorporating different types of landscape parameters in the<br />

JDTZ geomorphic analyses.<br />

Most of the geomorphic indices, such as the drainage basin asymmetry (AF),<br />

work best where each drainage basin is underlain by the same rock type (Keller and<br />

Pinter 2002). Therefore, conducting research focusing on analyzing several geomorphic<br />

indices in limited areas within the JDTZ might deliver significant relative tectonic<br />

activity results and may possibly expand the range of tectonic activity classes.<br />

Obtaining GPS elevation data of prominent landscape features and locations (i.e.<br />

actual GCPs) in the JDTZ are highly recommended to generate absolute DEMs of the<br />

study area in order to accurately compute the S mf and V f morphometric indices to<br />

precisely determine the tectonic activity in the JDTZ.<br />

Another point, which should be investigated in more detail, is the comparison of<br />

the new digital morphometric approach to an existing locations with known tectonic<br />

activity (i.e. activity classes) that has been determined by the morphometric analysis of<br />

landforms and topography (e.g. the Mojave Desert, California) to specify the difference<br />

in results between the two methods. In addition, this digital morphometric method in the<br />

JDTZ and other locations should be tested by using multiple DEMs produced by other<br />

sensors and of several ground resolutions.<br />

197


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Internet Resources<br />

ASTER Websites. Selected websites created by the USGS and NASA Jet Propulsion<br />

Laboratory (JPL) with complete description of the ASTER satellite instruments and<br />

imagery.<br />

http://asterweb.jpl.nasa.gov/<br />

http://eospso.gsfc.nasa.gov/<br />

http://terra.nasa.gov/<br />

http://www.terrainmap.com/rm22.html#top<br />

http://edcdaac.usgs.gov/aster/ast_l1b.asp<br />

http://edcdaac.usgs.gov/aster/ast14dem.asp<br />

http://edcdaac.usgs.gov/aster/asterprocessing.asp<br />

http://www.satimagingcorp.com/satellite-sensors/aster.html<br />

http://www.gds.aster.ersdac.or.jp/gds_www2002/index_e.html<br />

215


Appendix A<br />

Tables A.1 to A.5 list detailed results of both mountain front sinuosity (S mf ) and<br />

the valley floor width/height ratio (V f ) computations. In addition, the shape of each<br />

individual valley profile is described in an attempt to find the relationship between valley<br />

shapes and V f index results.<br />

Fronts/Valleys<br />

Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

Valley<br />

Profile#<br />

V f<br />

V f<br />

Class<br />

V f<br />

Mean<br />

V f<br />

Mean<br />

Class<br />

Dead Sea 1 67.70 1.07 1 1 1.18 2 0.54 1 U<br />

Valley<br />

Shape<br />

2 1.03 2 U<br />

3 0.51 1 - 2 U<br />

4 1.19 2 V<br />

5 0.19 1 V<br />

6 0.77 1 - 2 U<br />

7 0.47 1 V<br />

8 1.19 2 U<br />

9 0.28 1 V<br />

10 0.64 1 - 2 U<br />

11 0.47 1 V<br />

12 0.25 1 V<br />

13 0.32 1 V<br />

14 0.73 1 - 2 V<br />

15 0.18 1 V<br />

16 0.27 1 V<br />

17 0.41 1 V<br />

18 0.20 1 V<br />

19 0.36 1 V<br />

20 0.30 1 V<br />

21 0.25 1 V<br />

22 0.65 1 - 2 V<br />

Table A.1: The Dead Sea mountain front sinuosity (S mf ) and valley floor width to valley<br />

height ratio (V f ) results.<br />

216


Fronts/Valleys<br />

Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

Valley<br />

Profile#<br />

V f<br />

V f<br />

Class<br />

V f<br />

Mean<br />

V f<br />

Mean<br />

Class<br />

North Araba 1 64.63 1.21 1 1 0.38 1 0.50 1 V<br />

Valley<br />

Shape<br />

2 0.40 1 U<br />

3 0.38 1 V<br />

4 0.26 1 V<br />

5 0.34 1 V<br />

6 0.57 1 U<br />

7 0.69 1 V<br />

8 1.22 2 V<br />

9 0.85 1 V<br />

10 0.53 1 V<br />

11 0.61 1 V<br />

12 0.37 1 V<br />

13 0.26 1 V<br />

14 0.54 1 V<br />

15 0.33 1 U<br />

Table A.2: The North Araba mountain front sinuosity (S mf ) and valley floor width to<br />

valley height ratio (V f ) results.<br />

217


Fronts/Valleys<br />

Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

218<br />

Valley<br />

Profile#<br />

V f<br />

V f<br />

Class<br />

V f<br />

Mean<br />

V f<br />

Mean<br />

Class<br />

Dead Sea 1 132.32 1.14 1 1 1.18 2 0.53 1 U<br />

& North<br />

Araba<br />

2 1.03 2 U<br />

3 0.51 1 U<br />

Valley<br />

Shape<br />

4 1.19 2 V<br />

5 0.19 1 V<br />

6 0.77 1 - 2 U<br />

7 0.47 1 V<br />

8 1.19 2 U<br />

9 0.28 1 V<br />

10 0.64 1 - 2 U<br />

11 0.47 1 V<br />

12 0.25 1 V<br />

13 0.32 1 V<br />

14 0.73 1 - 2 V<br />

15 0.18 1 V<br />

16 0.27 1 V<br />

17 0.41 1 V<br />

18 0.20 1 V<br />

19 0.36 1 V<br />

20 0.30 1 V<br />

21 0.25 1 V<br />

22 0.65 1 - 2 V<br />

1 1 0.38 1 V<br />

2 0.40 1 U<br />

3 0.38 1 V<br />

4 0.26 1 V<br />

5 0.34 1 V<br />

6 0.57 1 U<br />

7 0.69 1 V<br />

8 1.22 2 V<br />

9 0.85 1 V<br />

10 0.53 1 V<br />

11 0.61 1 V<br />

12 0.37 1 V<br />

13 0.26 1 V<br />

14 0.54 1 V<br />

15 0.33 1 U<br />

Table A.3: The combined Dead Sea and North Araba mountain front sinuosity (S mf ) and valley<br />

floor width to valley height ratio (V f ) results.


Fronts/Valleys<br />

Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

Valley<br />

Profile#<br />

V f<br />

V f<br />

Class<br />

V f<br />

Mean<br />

V f<br />

Mean<br />

Class<br />

South Araba 1 35.94 1.16 1 1 0.35 1 0.56 1 V<br />

Valley<br />

Shape<br />

2 1.24 2 U<br />

22 0.29 1 V<br />

23 0.33 1 V<br />

24 0.15 1 V<br />

25 1.02 2 V<br />

2 3.62 1.21 1 3 0.58 1 0.75 1 - 2 U<br />

4 0.91 1 - 2 U<br />

3 32.14 1.28 1 5 0.53 1 0.35 1 U<br />

6 1.07 2 U<br />

7 0.79 1 - 2 U<br />

8 0.49 1 V<br />

9 0.11 1 V<br />

10 0.13 1 V<br />

11 0.21 1 V<br />

12 0.12 1 V<br />

13 0.26 1 V<br />

14 0.15 1 V<br />

15 0.41 1 U<br />

16 0.11 1 V<br />

17 0.42 1 U<br />

18 0.19 1 V<br />

19 0.29 1 V<br />

4 15.26 1.17 1 20 0.52 1 0.47 1 V<br />

21 0.42 1 V<br />

Table A.4: The South Araba mountain front sinuosity (S mf ) and valley floor width to<br />

valley height ratio (V f ) results.<br />

219


Fronts/Valleys<br />

Location<br />

Front#<br />

Length<br />

(Km)<br />

S mf<br />

S mf<br />

Class<br />

Valley<br />

Profile#<br />

V f<br />

V f<br />

Class<br />

V f<br />

Mean<br />

V f<br />

Mean<br />

Class<br />

Aqaba 1 10.52 1.12 1 1 0.17 1 0.16 1 U<br />

Valley<br />

Shape<br />

2 0.15 1 U<br />

2 14.60 1.22 1 3 0.38 1 0.32 1 U<br />

4 0.36 1 U<br />

5 0.23 1 U<br />

3 12.03 1.21 1 6 0.29 1 0.43 1 V<br />

7 0.58 1 - 2 U<br />

4 19.98 1.71 2 8 1.03 2 0.67 1 - 2 U<br />

9 1.02 2 U<br />

10 0.40 1 U<br />

11 0.24 1 U<br />

5 8.07 1.17 1 12 0.55 1 0.55 1 - 2 U<br />

6 10.12 1.07 1 13 0.15 1 0.18 1 V<br />

14 0.21 1 U<br />

7 10.62 1.22 1 15 0.07 1 0.14 1 V<br />

16 0.16 1 V<br />

17 0.18 1 U<br />

18 0.15 1 V<br />

8 21.31 1.25 1 19 0.82 1 - 2 0.26 1 U<br />

20 0.16 1 V<br />

21 0.13 1 V<br />

22 0.23 1 U<br />

23 0.19 1 V<br />

24 0.27 1 V<br />

25 0.15 1 V<br />

26 0.25 1 V<br />

27 0.25 1 U<br />

28 0.12 1 V<br />

9 22.30 1.13 1 29 0.09 1 0.21 1 V<br />

30 0.09 1 V<br />

31 0.55 1 U<br />

32 0.18 1 V<br />

33 0.40 1 U<br />

34 0.13 1 V<br />

35 0.12 1 V<br />

36 0.15 1 V<br />

Table A.5: The Aqaba mountain front sinuosity (S mf ) and valley floor width to valley<br />

height ratio (V f ) results.<br />

220

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