Abstracts with Programs - Geological Society of America

leakage. This study aims to use two surface geophysical techniques (conductivity and resistivity
profiling) to delineate the thickness of the landfill cap and locate any leachate plumes. The
electrical imaging survey was conducted on 6 parallel E-W lines across the length of the landfill,
using an ABEM Lund Imaging System. The surveys were made using a Wenner-α array with
2 meter electrode spacing. A conductivity survey, using a DualEM2S and DualEM4S, was
conducted over the same lines, followed by a survey conducted on 15 N-S lines perpendicular
to the original six lines. Several conductivity profiles were also made in a field just to the south
of the landfill. ArcGIS geospatial analysis modeling software was used to produce conductivity
maps for depths of 1, 2.2, 2.8 and 5.8 m (DualEM2S PRP, HCP and DualEM4S PRP and HCP,
respectively). All showed similar patterns. The conductivity values varied considerably (2.2-
461mS/m). Several N-S linear anomalies were evident extending outside of the landfill towards
the adjacent field. On the resistivity profiles, a number of low resistivity anomalies, near the
surface, suggested that the landfill cap was not intact. Deeper low resistivity anomalies (> 5
meters) suggested the presence of leachate and was consistent with the known position of
leachate within the landfill. The conductivity data correlated well with the resistivity surveys to
delineate inconsistencies in the landfill cover and indicated the presence of leachate which may
affect the field adjacent to the landfill.
18-8 BTH 14 Joshi, Siddharth Dilip [218499]
GEO-ELECTRIC INVESTIGATION OF UNDERGROUND LEACHATE DISTRIBUTION AT A
CLOSED LANDFILL IN SOUTHWESTERN ONTARIO, CANADA
JOSHI, Siddharth Dilip1 , YANG, Jianwen1 , SERERES, Clayton2 , and TAMR, Radwan2 ,
(1) Earth and Environmental Sciences, University of Windsor, 401 Sunset Avenue - University
of Windsor, Windsor, ON N9B 3P4, Canada, joshis@uwindsor.ca, (2) GENIVAR Inc, 4510
Rhodes Driver, Suite 720, Windsor, ON N8W 5K5, Canada
Contamination due to landfill leachate can cause disastrous effects to aquifers used for
groundwater supply. In this study, two geo-electric techniques were employed to investigate the
underground leachate distribution and the subsurface geology at a closed site in southwestern
Ontario, Canada. Conductivity mapping was first conducted over the study site using a frequencydomain
EM terrain conductivity meter, which reveals an anomalous zone with the apparent
conductivity values ranging between 130-500mS/m, concentrated in the 200m (S-N) by 80m
(W-E) rectangle area at western half of the site. The DC resistivity survey was then carried
out in the same area with 8 S-N profiles and 3 W-E profiles measuring 200m in length using a
Wenner-α configuration. This arrangement of electrodes has an approximate exploration depth of
30m, which aids in outlining the waste and upper sand aquifer, the underlying silt/sand aquitard,
and the lower sand aquifer. Our resistivity survey results exhibit an inconsistency in the clay cap
thickness on almost all the profiles conducted. The results also indicate that the contamination
plume is mainly travelling southwards at the base of the upper aquifer just below the waste, with
a minor vertical component into the upper weathered portion of the silt/sand aquitard at some
locations. No contamination plumes seem to exist in the lower sand aquifer. These findings are
critical in assessing the current leachate conditions and in evaluating the existing compliance
monitoring plan for potential implementation at the site or other sites in elsewhere.
18-9 BTH 15 Estifanos, Biniam Haileab [218655]
GEOPHYSICAL PROSPECTING FOR CONCEALED KARST NEAR BELLEVUE, OH
ESTIFANOS, Biniam Haileab and STIERMAN, Donald J., Department of Environmental
Sciences, University of Toledo, 2801 West Bancroft Street MS604, Toledo, OH 43606,
Biniam.Estifanos@rockets.utoledo.edu
The Bellevue area, Ohio is characterized by sinkholes and dolines that allow surface water to
rapidly drain into the carbonate aquifer. During episodes of excessive precipitation, part of the
state Route 269 floods due to groundwater welling up. Ver Steeg and Yunck (1932) report water
seeping in areas without visible sinkholes causing 3-4 foot high flood during the spring of 1930.
We are using gravity and electrical resistivity methods to investigate concealed karst and
underground conduits north of Bellevue. We occupied closely spaced (20 and 50 m) gravity
stations along three east-west profiles, two adjacent to a topographic depression we interpret
as a sinkhole complex. At this stage there is only a marginal suggestion of gravity lows that
might indicate subsurface voids. Four dipole-dipole resistivity profiles totaling 2 km show only
one obvious void, adjacent to a sinkhole. However, most resistivity measurements were made
during the drought of summer 2012, making the distinction between voids and carbonate
bedrock difficult. Repeat measurements will be conducted when the groundwater rises. A rise in
groundwater level will convert air-filled voids (high resistivity) to water-filled voids (low resistivity).
Electrical resistivity was used to detect air and water filled cavities at Seneca Caverns to the
south, confirming this methodology.
In January 2013, the static water level at USGS monitoring well at Bellevue rose 10 feet in
response to 2 inches of precipitation. Stage level recorded at the Huron River east of the city
shows a strong agreement with the static water level rise but dropped fast after the peak flow
while the groundwater water level remained constant. The strong response of the groundwater
to precipitation suggests that karstic porosity is quite low. Knowledge of the size and extent
of the concealed karst will help in reducing impact of pollution on groundwater resources and
delineating hazard prone areas.
18-10 BTH 16 Gerson, Laura M. [218426]
USING GEOPHYSICAL METHODS TO STUDY KARST IN URBAN SPRINGFIELD, MISSOURI
GERSON, Laura M., Geoscience, Missouri State University, Springfield, MO 65897,
gerson9576@live.missouristate.edu, MICKUS, Kevin, Geology, Missouri State University,
Springfield, MO 65897, and GOUZIE, Douglas, Department of Geology, Missouri State
University, 901 S. National Ave, Springfield, MO 65897
Southwestern Missouri is located on the Springfield Plateau which mainly consists of Paleozoic
carbonates and minor amounts of siliceous sediments. The dominant formation exposed in the
area is the Mississippian Burlington-Keokuk Limestone which is nearly horizontal and susceptible
to the formation of karst features such as sinkholes and caves. Near surface geophysical methods
are useful in determining the location and nature of karst features, especially those that are not
visible on the surface.
Electrical resistivity, gravity, and very low frequency electromagnetics have been collected
along a trend of mapped sinkholes where previous dye traces have indicated a large, long
underground passage. Inverse modeling of the electrical resistivity profiles indicates pinnacles
of highly resistive material with areas of low resistive material between them, indicating possible
fractures in the bedrock. Some of the resistivity lows could be buried sinkholes. Depth of karst
features varies from 5-12 meters and deeper. Two-dimensional gravity modeling shows a
similar trend in subsurface topography. Both methods show a similar roughly linear trend that
correlates with known sinkholes. Very low frequency electromagnetics does not correlate as
well due to its susceptibility to noise, but one-third of the profiles do correlate with the electrical
resistivity profiles.
SESSION NO. 19
18-11 BTH 17 Yaqoob, Muthanna Yousif [218626]
DETECTION OF BEDROCK FRACTURES AND JOINTS BENEATH COVER: GEOPHYSICAL
APPROACHES TO AN ENGINEERING GEOLOGY PROBLEM
YAQOOB, Muthanna Yousif and SAUCK, William A., Geosciences, Western Michigan Univ,
Kalamazoo, MI 49008, muthanna.y.yaqoub@wmich.edu
This research used geophysical methods to detect the presence of sub-vertical failure planes,
their direction(s), and their frequency in bedrock beneath soil or glacial drift overburden. Azimuthal
measurements using the seismic, electrical resistivity (ER), electromagnetic conductivity and
ground penetrating radar (GPR) were made to evaluate which techniques might provide the best
indication of the bedrock joints, faults, or shear zones. Measurements were made at multiple
sites near each of three locations: Jackson, Alpena, and Grand Ledge, Michigan. The first two
are former limestone quarries and the third is underlain by sandstone. Seismic measurements
began with one or two linear refraction spreads, used to establish thickness of overburden and
identify the S waves. The azimuthal seismic was done by placing the 24 geophones around a
10 or 15m radius circle (15 degree intervals), with the shot point in the center, measuring arrival
times of the P and S waves. The EM-31 conductivity was used to quickly determine that there
were no wires or pipes in or near the survey circle, as well as to profile along the diameters of the
circle at 12 different azimuths. The square array was used for the resistivity measurements in the
same circle, with the diagonal of the square being the circle diameter. This array was rotated to 12
unique azimuths at 15° intervals. GPR was tested at one site using 100 MHz antennae. The Rx
was at the center, and the Tx was moved around the circumference of the circle at 15° intervals,
to measure the arrival times of the ground wave. Reference measurements of the strikes of failure
planes were made using a Brunton compass and photographs at adjacent bedrock exposures.
Verification of results was done by comparing the geophysical results and the measured
strikes and dips of the nearby exposures of the joint systems. The preliminary analyses of the
results showed coincidence of the tests results with the strike measurements in some areas,
whereas others did not. Some of the methods are very sensitive to variations in thickness of the
overburden. These effects, as well as lateral resistivity gradients in the bedrock and overburden
can apparently cause false indications of fracture systems.
18-12 BTH 18 Mogren, Saad [217949]
REACTIVATION OF THE ABU-JIFAN FAULT BORDERING THE RAYN ANTICINES IN EASTERN
SAUDI ARABIA: GRAVITY MODELING OF A SEISMOGENIC CRUST
MOGREN, Saad and MUKHOPADHYAY, Manoj, Geology and Geophysics Department, King
Saud University, PO Box 2455, Riaydh, 11451, Saudi Arabia, smogren@ksu.edu.sa
The Abu-Jifan Fault truncates the Rayn anticlines along an 1100 km long margin within the
Rayn Microplate in eastern Saudi Arabia. This set of anticlines is comprised of six sub-parallel
super-giant anticlines, including the Ghawar uplift. Crust on either side of the fault is seismically
active; width of the seismic zone varies from 170 – 220 km. The Ghawar anticline is however
seismically intensely active which is supposed to be an outcome of fluid-extraction induced
seismicity. Top part of this seismogenic crust is currently intensely deformed in consequence
to induced seismicity below the Rayn anticlines and prevailing east-west stress. Here we argue
that induced seismicity plays an important role in reactivating the Proterozoic east-west faults
in the deeper crust. An integrated geophysical modeling approach is next adopted to derive the
deeper geometry of the Abu-Jifan Fault that slices the seismogenic crust south of the Ghawar
anticline. Geophysical data sets include: seismic velocity analysis for crust and top- lithosphere,
IRIS seismic line interpretation for the Arabian Platform as well as the crustal structure and upper
mantle stratigraphy from receiver function analysis and shear-wave splitting studies, conventional
seismic interpretation for deep sedimentary layers, isopach map prepared for the major sediment
lithologies, and the relevant density information for the major formations deduced from density
logs obtained from drill holes in the oil fields. Their combined use is found to be a potentially
powerful tool for investigating the deeper fault geometry which is modeled by gravity inversion
along a profile in central part of the fault. Gravity modeling suggests that the Abu-Jifan Fault is a
deep penetrative strike-slip fault, demarcating a denser crust along its north margin.
SESSION NO. 19, 1:30 PM
Thursday, 2 May 2013
T8. Addressing Environmental Aspects of Geology:
Research, Pedagogy, and Public Policy (Posters)
Schneider Hall, Courtyard
19-1 BTH 19 Musch, Steven C. [218735]
INTERACTIONS BETWEEN DUNE TRAILS AND CIRSIUM PITCHERI HABITAT
MUSCH, Steven C., HILVERDA, Elaine, LEGGE, Evan A., STRYDHORST, Natasha A., and
VANDERBILT, Lucas E., Geology, Geography and Environmental Studies, Calvin College,
3201 Burton St SE, Grand Rapids, MI 49546, scm3@students.calvin.edu
This study looked closely at the conditions of a threatened species habitat when it exists among
unmanaged dune trails. A fourteen-acre plot of land on the eastern coast of Lake Michigan was
recently purchased for conversion from private land into a dune preserve. This property includes
hummocky foredunes, blowouts, and two stabilized parabolic dunes, and it serves as critical
habitat for the threatened species Cirsium Pitcheri (Pitcher’s Thistle). To determine the condition
of the habitat, a study was done to locate all specimens, gauge the age of the population, and
explore the effects of anthropogenic disturbance. GPS mapping was used to create an inventory
of all specimen locations and all observed trails through the property. Measurements were taken
of each plant to gauge the age of the population and the GPS results were assembled in a map to
observe the density. Our results showed 206 Cirsium Pitcheri specimens, most of which appeared
to range from three to six years of age. Spatial analysis of the GPS data showed two distinct
groupings of plants along with numerous unmanaged trails. The largest trail, which divided the
two groups of plants, extended from the low point between two large parabolic dunes out to the
beach. We observed that the heavy use of this trail combined with an extension of the stabilized
portion of the dunes produced unfavorable conditions for Cirsium Pitcheri. With these results we
were able to provide the new property owners with important information regarding critical habitat
of Cirsium Pitcheri.
2013 GSA North-Central Section Meeting 25