Download Volume II Accomplisments (28 Mb pdf). - IRIS

More documents

Recommendations

Info

$Refraction - IRIS$

Evolution of Caribbean – South American Plate Boundary from Surface Wave Tomography Meghan S. Miller (University of Southern California), Alan Levander (Rice University), Fenglin Niu (Rice University) We have measured shear wave velocity structure of the crust and upper mantle of the Caribbean – South American boundary region by analysis of fundamental mode Rayleigh waves in the 20-100s period band recorded at the BOLIVAR/GEODINOS stations from 2003 to 2005. The model shows lateral variations that primarily correspond to tectonic provinces and boundaries. A clear linear velocity change parallels the plate bounding dextral strike-slip fault system along the northern coast of Venezuela, illustrating the differences between the South American continental lithosphere, the Venezuelan archipelago, and the Caribbean oceanic lithosphere. At depths up to 120 kilometers beneath the Venezuelan Andes and the Maracaibo block there is evidence of underthrusting of the Caribbean plate, but there is no other evidence of subduction of the Caribbean plate beneath the South American plate. In eastern Venezuela linear crustal low velocities are associated with the fold and thrust belts whereas as higher crustal velocities are imaged in the Guayana shield lithosphere. The subducting oceanic part of the South American plate is imaged beneath the Antilles Arc. The surface wave images combined with seismicity data suggest shear tearing of the oceanic lithosphere away from the buoyant continental South American plate offshore of northeastern Venezuela. The continental lithosphere south of the slab tear is bent down towards the plate boundary in response to the propagating tear in the lithosphere. We interpret a nearly vertical low velocity “column” west of the tear centered beneath the Cariaco Basin, with three dimensional asthenospheric flow around the southern edge of the subducting oceanic lithosphere, with the asthenosphere escaping from beneath continental South America, and rising into the plate boundary zone. The complex plate boundary structure is best examined in three-dimensions. We discuss the new surface wave tomographic inversion in the context of results from other researchers including local seismicity, teleseismic shear wave splits, and interpretations from active source profiling. Acknowledgements: BOLIVAR was funded by grants EAR0003572 and EAR0607801 from the NSF Continental Dynamics Program, and funding to our Venezuelan colleagues from CONICIT, the Venezuela Science Foundation, and PDVSA. Surface wave tomography model illustrating the structure of the South American mantle lithosphere as viewed from the northwest. The yellow dots are relocated seismicity, which define the Paria cluster and the location of the subducted oceanic lithosphere beneath the Antilles arc tearing away from the continental lithosphere along the Caribbean-South American plate boundary. II-154 | 2010 IRIS Core Programs Proposal | Volume II | Lithosphere, Lithosphere/Asthenosphere Boundary
Subducted Oceanic Asthenosphere and Upper Mantle Flow beneath the Juan de Fuca Slab R. M. Russo (University of Florida) Many studies have shown that typical oceanic lithosphere is underlain by a well developed asthenosphere characterized by slow seismic velocities from ~100-250 km depth. However, the fate of the oceanic asthenosphere at subduction zones is poorly understood. I show here using shear wave splitting of S waves emanating from earthquakes in the Juan de Fuca slab that upper mantle asthenospheric anisotropy beneath the slab is consistent with the presence of two distinct subducted asthenospheric layers, one with fast shear trends parallel to the subduction trench, and a second, deeper layer with fast upper mantle fabrics parallel to the motion of the Juan de Fuca plate with respect to the deeper mantle. The consistent orientation of unsubducted Pacific asthenospheric anisotropy in the direction of current plate motion implies that the trench-parallel sub-slab anisotropy develops when the lithosphere subducts. References Russo, R. M., Subducted oceanic asthenosphere and upper mantle flow beneath the Juan de Fuca slab, Lithosphere, 1, 195-205, 2009. Block diagram showing Juan de Fuca slab geometry (green meshed surface), and top-of-slab depth contours (heavy blue dashed lines, bottom). Source side S splitting measurements are compatible with presence of two anisotropic layers beneath the Juan de Fuca slab: a layer immediately beneath the slab which is characterized by trench-parallel fast shear azimuths, and a deeper layer with fast shear trends parallel to the motion of the Juan de Fuca plate with respect to assumed fixed hotspots (Gripp and Gordon, 2003). Orange arrows schematically show the anisotropy and possibly upper mantle flow directions in these two layers. 2010 IRIS Core Programs Proposal | Volume II | Lithosphere, Lithosphere/Asthenosphere Boundary | II-155
Page 1 and 2:
volume ii - accomplishments Facilit
Page 3 and 4:
volume ii - accomplishments Facilit
Page 5 and 6:
CONTENTS Introduction..............
Page 7 and 8:
Non-Volcanic Tremor along the Oaxac
Page 9 and 10:
Detecting the Limit of Slab Break-o
Page 11:
Lower Mantle, Core-Mantle Boundary
Page 14 and 15:
• Non-Earthquake Seismic Sources
Page 16 and 17:
acoustics community by permitting a
Page 18 and 19:
Near-Surface Environments - Hazards
Page 20 and 21:
Why Do Faults Slip? Emily Brodsky (
Page 22 and 23:
Another probe of fault evolution is
Page 24 and 25:
to provide a best match with the Gl
Page 26 and 27:
tectonic disruption and mass accumu
Page 28 and 29:
W3 ∆ 5 . A number of intriguing r
Page 30 and 31:
thermal and compositional effects r
Page 33 and 34:
Towards a Global School Seismic Net
Page 35 and 36:
On-Line Seismology Curriculum for U
Page 37 and 38:
Teachers on the Leading Edge: Earth
Page 39 and 40:
USArray Education and Outreach in S
Page 41 and 42:
From an IRIS Lecture Tour to a Gene
Page 43 and 44:
Explorer Series Robert Bartolotta (
Page 45 and 46:
Workshop “Earth System Science fo
Page 47 and 48:
The IRIS Internship Cycle: From Int
Page 49 and 50:
Community-Outreach Efforts in Data
Page 51 and 52:
Site Reconnaissance for Earthscope
Page 53 and 54:
jAmaseis: Seismology Software Meeti
Page 55 and 56:
Near Real-Time Simulations of Globa
Page 57 and 58:
FuncLab: A MATLAB Interactive Toolb
Page 59 and 60:
Five Years of Distributing the Seis
Page 61 and 62:
IRIS DMS Data Products, Beyond Raw
Page 63 and 64:
Local Earthquakes in the Dallas-Ft.
Page 65 and 66:
Epicentral Location Based on Raylei
Page 67 and 68:
Analysis of Spatial and Temporal Se
Page 69 and 70:
Exceptional Ground Motions from the
Page 71 and 72:
The 2010 Mw7.2 El Mayor-Cucapah Ear
Page 73 and 74:
Effects of Kinematic Constraints on
Page 75 and 76:
Imaging of the Source Properties of
Page 77 and 78:
Teleseismic Inversion for Rupture P
Page 79 and 80:
The Global Aftershocks of the 2004
Page 81 and 82:
The 17 July 2006 Java Tsunami Earth
Page 83 and 84:
Seismic Cycles on Oceanic Transform
Page 85 and 86:
Migration of Early Aftershocks Foll
Page 87 and 88:
Apparent Stress Variations at the O
Page 89 and 90:
Automated Identification of Telesei
Page 91 and 92:
Evaluating Ground Motion Prediction
Page 93 and 94:
Tremor Monitoring Aaron Wech (Unive
Page 95 and 96:
Slow Slip and Tremor in the Norther
Page 97 and 98:
0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2
Page 99 and 100:
Intimate Details of Tremor Observed
Page 101 and 102:
Global Search of Triggered Tremor a
Page 103 and 104:
Slab Morphology in the Cascadia For
Page 105 and 106:
Source Analysis of the Memorial Day
Page 107 and 108:
Iceberg Tremor and Ocean Signals Ob
Page 109 and 110:
Elucidating the Stick-Slip Nature o
Page 111 and 112:
Probing the Atmosphere and Atmosphe
Page 113 and 114:
Volcanic Plume Height Measured by S
Page 115 and 116: Eruption Dynamics at Mount St. Hele
Page 117 and 118: A Search for the Lunar Core Using A
Page 119 and 120: Seismic Imaging of the Mt. Rose Fau
Page 121 and 122: Structure of the California Coast R
Page 123 and 124: Temporal Variations in Crustal Scat
Page 125 and 126: High-Resolution Locations of Trigge
Page 127 and 128: Adjoint Tomography of the Southern
Page 129 and 130: Crustal Structure of the High Lava
Page 131 and 132: Controlled Source Seismic Experimen
Page 133 and 134: Structural Interpretations Based on
Page 135 and 136: Optimized Velocities and Prestack D
Page 137 and 138: 40 Crustal Structure beneath the Hi
Page 139 and 140: Controlled-Source Seismic Investiga
Page 141 and 142: Northward Thinning of Tibetan Crust
Page 143 and 144: An Integrated Analysis of an Ancien
Page 145 and 146: Crustal Velocity Structure of Turke
Page 147 and 148: Ambient Noise Tomography of the Pam
Page 149 and 150: Ambient Noise Monitoring of Seismic
Page 151 and 152: Mushy Magma beneath Yellowstone Ris
Page 153 and 154: Imaging the Seattle Basin to Improv
Page 155 and 156: Developing a Database of ENA Ground
Page 157 and 158: Lithospheric Layering in the North
Page 159 and 160: eflective zones on depthmigrated se
Page 161 and 162: FischerFig05.pdf 1 2/8/10 12:31 PM
Page 163 and 164: S-Velocity Structure of Cratons, fr
Page 165: Seismic Structure of the Crust and
Page 169 and 170: Detecting the Limit of Slab Break-o
Page 171 and 172: Pn Tomography of the Western United
Page 173 and 174: 3-D Isotropic Shear Velocity Model
Page 175 and 176: Seismic Anisotropy Associated with
Page 177 and 178: Anisotropy in the Great Basin from
Page 179 and 180: Source-Side Shear Wave Splitting an
Page 181 and 182: S-Velocity Structure of the Upper M
Page 183 and 184: Velocity Structure of the Western U
Page 185 and 186: Segmented African Lithosphere benea
Page 187 and 188: Imaging the Mantle Wedge in the Cen
Page 189 and 190: A Slab Remnant beneath the Gulf of
Page 191 and 192: Imaging the Southern Alaska Subduct
Page 193 and 194: Opposing Slabs under Northern South
Page 195 and 196: Effect of Prior Petrological Constr
Page 197 and 198: Global Azimuthal Seismic Anisotropy
Page 199 and 200: The Stratification of Seismic Azimu
Page 201 and 202: Upper Mantle Anisotropy beneath the
Page 203 and 204: The Teleseismic Signature of Fossil
Page 205 and 206: Seismic Anisotropy under Central Al
Page 207 and 208: Stress-Induced Upper Crustal Anisot
Page 209 and 210: Tau-p Depropagation of Five Regiona
Page 211 and 212: Mapping the Upper Mantle with the S
Page 213 and 214: Upper Mantle Structure of Southern
Page 215 and 216: The Africa-Europe Plate Boundary in
Page 217 and 218:
The Isabella Anomaly Imaged by Eart
Page 219 and 220:
Tomographic Image of the Crust and
Page 221 and 222:
Small-Scale Mantle Heterogeneity an
Page 223 and 224:
Mantle Heterogeneity West and East
Page 225 and 226:
New Geophysical Insight into the Or
Page 227 and 228:
The Plume-slab Interaction beneath
Page 229 and 230:
Imaging the Shear Wave Velocity "Pl
Page 231 and 232:
Slab Fragmentation and Edge Flow: I
Page 233 and 234:
Mantle Shear-Wave Velocity Structur
Page 235 and 236:
Discordant Contrasts of P- and S-Wa
Page 237 and 238:
Upper Mantle Discontinuity Topograp
Page 239 and 240:
Edge-Driven Convection beneath the
Page 241 and 242:
Imaging Attenuation in the Upper Ma
Page 243 and 244:
Three-Dimensional Electrical Conduc
Page 245 and 246:
Core-Mantle Boundary Heat Flow Thor
Page 247 and 248:
Constraints on Lowermost Mantle Ani
Page 249 and 250:
Localized Double-Array Stacking Ana
Page 251 and 252:
Waveform Modeling of D" Discontinui
Page 253 and 254:
Absence of Ultra-Low Velocity Zones
Page 255 and 256:
Moving Seismic Tomography Beyond Fa
Page 257 and 258:
A Three-Dimensional Radially Anisot
Page 259 and 260:
The Importance of Crustal Correctio
Page 261 and 262:
Slabs Do Not Go Gentle Karin Sigloc
Page 263 and 264:
Localized Temporal Change of the Ea
Page 265 and 266:
Core Structure Reexamined Using New
Page 267 and 268:
Large Variations in Travel Times of
Page 269 and 270:
Observations of Antipodal PKIIKP Wa
Page 271 and 272:
Regional Variation of Inner Core An
Page 273:
Wide-Scale Detection of Earthquake
show all

Download Volume II Accomplisments (28 Mb pdf). - IRIS

Create successful ePaper yourself

Delete template?

Save as template?