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22nd EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 29 Mar 2009 - 02 Apr 2009
- Location: Forth Worth, Texas, USA
- Published: 29 March 2009
41 - 60 of 124 results
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Shear-Wave Velocity as an Indicator of Increased Stress and Failure Potential Associated with Dissolution-Mining Voids
Authors S. Sloan, R. Miller, J. Ivanov and S. WaltersThe use of dissolution wells for mining salt has been common practice for over a century, leaving behind brine-filled “salt jugs” or voids in the subsurface which, over time, can migrate through overlying rock formations, potentially leading to sinkhole formation and public safety hazards. In an effort to determine the relative range of stress on the roof rock above these jugs at various stages of failure, evaluate the extent of void migration, and aid in remediation planning, shear-wave reflection surveys were conducted at a well field near Hutchinson, Kansas, where drill-confirmed dissolution features exist in the 125-m deep Hutchinson Salt Member.
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Detailed Imaging of Near-surface Faulting Structure using Land Streamer
Authors T. Inazaki and T. NakanishiDelineation of near-surface deformation structure is essential to characterize the recent behavior
of active fault system and to estimate its near future activity. Although a combination of exploratory
trenching and drilling has been widely adopted to reveal deformation history of active faults for the
paleoseismological studies in Japan, it was difficult to delineate the faulting structure by such “pinpoint”
surveying.
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Shallow Fault Detection Using 3-D Seismic Reflection Surveys
Authors B. Hoekstra, R. Huggins and C. LippusA 3-D seismic survey was performed to evaluate the practicality of this method to map very shallow objectives (less than 100 m). The survey was conducted in an area near San Francisco Bay where the geology consisted mainly of fluvial/deltaic geology. The site was located between the Hayward and San Andreas faults.
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New Approaches to Topographic Gravity Corrections
More LessThe conventional approach of computing a gravity topographic correction from digital elevation
models (DEM) involves creating a correction grid at a station by means of interpolation. Obviously, the
interpolation process introduces errors in the estimated elevation of the grid points that result in noise of
the computed topographic correction.
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Thermo-Mechanical Analysis of Roller Compacted Concrete (RCC) Dams
Authors A. Shamsaei, M. Ghaemian and M. AzimfarIn this paper a procedure for two-dimensional unsteady thermo-mechanical analysis of layered
structures is presented, allowing the determination of the temperature and stress field at each step the
construction period. The finite element method is employed in the methodology. Numerical
simulation are focused on concrete structures, particularly roller compacted concrete (RCC) dams. A
time varying elasticity modulus is introduced in the model. One case study is presented and analysis
under different design approaches.
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A New High Resolution Magnetic Gradient Survey for Kimberlites
Authors T.J. Gamey, J. Norton and G. LockhartIn July 2008, Indicator Minerals flew a high resolution magnetic gradient survey near the Hamlet
of Kugaaruk, Nunavut looking for kimberlite deposits. This survey was designed as a potential
replacement for ground-based geophysics with a higher data resolution and collection speed.
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Transverse Total Magnetic Field Gradiometer Marine Survey in Hawaii: The Quasi-Analytic Signal Approach and Multi-Channel Total Field DIPOLE MODELING
Authors M. Tchernychev, R. Johnson and J. JohnstonIn this paper we present two techniques for Transverse Gradiometer (TG) data processing and
their practical application. Using our method, the transverse gradient is measured using dual sensors.
The longitudinal gradient is obtained using profile data history and the vertical gradient component is
computed synthetically based on 2-D potential field theory using the Total Field along the profile.
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Application of Microgravity at Archaeological Sites in Israel: Some Estimation Derived from 3-D Modeling and Quantitative Analysis of Gravity Field
By L. EppelbaumGravity survey is comparatively rarely applied for searching of hidden ancient targets. It is
caused mainly by small geometric size of the desired archaeological objects and various noises
complicating the observed useful signal. At the same time, development of modern generation of field
gravimetric equipment allows to register microGal (10-8 m/s2) anomalies that offer a new challenge in
this direction. Correspondingly, an accuracy of gravity variometers (gradientometers) is also sharply
increased.
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Detection of Ferro-Metallic Objects from Magnetic Data Using a Scaled Hopfield Neural Network
Authors A. Salem, T. El.Tobely, A. El-Kabbani, A. El Maksood and F. SolimanThe purpose of the present paper is to investigate the Hopfield neural network as a flexible detection method of Ferro-magnetic sources from magnetic anomaly data. The observed magnetic anomaly is approximated over a steel drum by an equivalent dipole source. The Hopfield network was used to obtain the magnetic moment at a set of regular locations. For each location, the Hopfield network reaches its stable state and the location of minimum Hopfield energy signifies the target location. To escape from the local minimum of the network energy function, the scaled input technique is proposed.
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On-the-go Vertical Sounding of Agricultural Fields using EMI Sensors
Authors A. Mat Su, V. Adamchuk and R. EigenbergSpatial variability of topsoil depth is of interest to many agricultural practitioners since it relates to the ability of soil profile to accumulate water and nutrients. Conventional on-the-go mapping of apparent soil electrical conductivity provides valuable information related to the spatial variability of soils, but does not always allow detecting differences that occur with depth.
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Optimization of seismic data processing flow for tunnel detection using energy spectrum and stacking spectral energy peaks of overlapping arrays
Authors O. Kovin, N. Putnam and E. TorgashovAnalyses of seismic data demonstrate increasing acoustic energy recorded above an
underground tunnel. This is attributed to internal reverberations within the tunnel,
reflection (backscattering), and wave conversion. Soil heterogeneity, changes in
geophone-to-ground coupling and the shape of the generated signal introduce fluctuations
into the trace spectrum.
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Geophysical Delineation of the Groundwater Potentials in a Basement Complex Terrain: A Case Study of Imope and Environs, Southwestern Nigeria
Authors G. Mosuro, E. Ayolabi, O. Bayewu, M. Oloruntola and G. OgungbesanVertical Electrical Sounding (VES) has been used as a tool to study the groundwater potentials exploration pattern of Imope, Igaran, Aparaki and Idofe villages, in southwestern Nigeria. A total number of eighty VES stations were established on the study areas covering 4,375,000m2 using the schlumberger configuration with electrodes spacing varying from 50 to 120m. The surveys were carried out on equal grids of 250 by 250m.
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A New Approach to Predict Hydrogeological Parameters Using Shear Waves from Multichannel Analysis of Surface Waves Method
Authors A. Cameron and C. KnappA high resolution P-wave seismic reflection survey was performed at the P Reactor Area, Savannah River Site, South Carolina in order to delineate and predict migration pathways of a large contaminant plume including trichloroethylene that originates from the northwest section of the reactor facility located within the Upper Atlantic Coastal Plain.
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Subsurface Brine Detection and Monitoring in West Point, Kentucky, with 2D Electrical Resistivity Tomography
Authors R. Henderson, M. Unthank, D. Zettwoch and J. Lane Jr.Ongoing investigations of the Fort Knox public water supply well field in West Point, Kentucky revealed an increase in chloride concentrations within the aquifer system due to improperly abandoned natural gas exploration wells. The site and regional geology consists of unconsolidated glacial outwash approximately 30- to 40-m thick, underlain by shale and porous limestone.
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High Resolution Hybrid-Source Magnetotellurics Along the Eastern Margin of the Santo Domingo Sub-Basin within the Rio Grande Rift, New Mexico
By J. GunterDuring SAGE, (Summer of Applied Geophysical Experience), 2004 eight high resolution hybrid-source magnetotelluric soundings were collected at 100 meter intervals along an east-west profile perpendicular to the La Bajada fault, a major east bounding fault of the Santo Domingo sub-basin.
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Year 2008 of an Ongoing Investigation of the San Marcos Pueblo, New Mexico
Authors N. Tucker, S. Finn, N. McMahon, M. Bannister, M. Beachly, N. Garcia and D.K. McPheeStudents of the Summer of Applied Geophysical Experience (SAGE), a field-based educational
program in applied geophysical methods, studied the 60-acre San Marcos Pueblo archaeological site in
northern New Mexico as part of an ongoing geophysical investigation. In 2008 ground penetrating radar
(GPR), seismic refraction, electromagnetic and magnetic surveys focused on parts of the pueblo in use
during the early colonial period, prior to the pueblo revolt in 1680 when the population of the pueblo
approached its peak.
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Seismic Tomography Applied to Archaeological Excavation: Field Tests at the Kiuic Site, Yucatan, Mexico
Authors W. Fontaine, J. Harris and G. BeyIn June 2008, a seismic survey was conducted at the Kiuic archaeological site in the Central Hills District of southwest Yucatan, Mexico. The main target of the survey was a Maya temple pyramid (approximately 18 m x 16 m) consisting of two stepped platforms. A seismic tomography data set, yielding a total of 1320 raypaths through the structure, was acquired using a 12-channel engineering seismograph and a 1.8-kg sledgehammer source.
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Assessing Sinkhole Potential at Wink and Daisetta Using Gravimetry and Radar Interferometry
Authors J. Paine, S. Buckley, E. Collins, C. Wilson and W. KressLarge sinkholes (50 to 200 m in diameter) formed over Permian bedded salt near Wink in western Texas in June 1980 and May 2002 and on the flank of a salt dome at Daisetta, Texas in May 2008. Residents,
government officials, and industry representatives would like to better understand the potential for sinkhole formation and growth.
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Subsurface Characterization in a Karstified Limestone Area Using Ground-Penetrating Radar: Bonaire, Netherlands Antilles
Authors M. de Kleine and M. BakkerOn the island Bonaire, Netherlands Antilles, a ground-penetrating radar (GRR) survey combined
with geological reconnaissance has been executed in order to characterize an area with emerged
karstified limestone reefs. The purpose of the study was the mapping the presence and distribution of
caves in order to make an ecological and geotechnical evaluation of this area, prior to development of
this area for housing.
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Spatial Mapping of Submerged Cave Systems by Means of Airborne Electromagnetics
Authors R. Supper, A. Ahl, K. Motschka, D. Ottowitz, P. Bauer, G. Merediz Alonso and B. JochumKarst aquifers represent important but very vulnerable sources for water supply to a significant
part of the earth’s population. For sustainable use of these resources, development of integrated
management tools based on numerical groundwater models is required. In principle karst aquifers are
characterized by the presence of two distinct flow domains: the limestone matrix and the karst conduits.
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