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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
1 - 20 of 124 results
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Applications of New Technologies of Groundbased Interferometric Radar to the Study of Cultural Heritage Buildings
Authors M. Marchisio, G. Ranieri, G. Bernardini, L. D‘Onofrio, P. Farina, M. Manunta and L. PiroddiDifferential Synthetic Aperture Radar Interferometry is a technique that, by making the phase difference of
SAR image pairs, allows to extract the information relevant to the earth surface displacements.
The result of the phase difference, referred to as Interferometric Phase or Interferogram, contains different
terms: the deformation phase term, a topographic phase contribution, an atmospheric phase term and the
noise contibution.
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Three Step Depth Focussed Inversion as a Tool to Resolve Small Resistivity Contrasts by ERT
Authors U. Noell, T. Günther and M. FurcheIn more recent times Electrical Resistivity Tomography (ERT) has become a valuable tool for many
environmental research themes. Within these topics the resistivity contrasts of the different layers and
zones are of importance, i.e. sand, clay, water salinity and preferential infiltration pathways are quite
small. Inclusions with such small resistivity contrasts to the surrounding are difficult to resolve by ERT
inversion and typically the following problems occur: 1.) the true resistivity contrasts are underestimated
2.) the size of the anomalous zone is overestimated 4.) fake anomalies arise beside and between the true
anomalous zones. 4.) surface heterogeneities infer fake anomalies into the subsurface.
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Improved Monte Carlo Inversion of Resistivity Data
Authors C. Piatti, D. Boiero, A. Godio and L.V. SoccoInversion of 1D technique (VES and TDEM) by using Global Search Procedures (GSPs) as proved to be
effective in evidencing local minima and equivalence problems, evaluating non-uniqueness in
the solution, and estimating the values and uncertainties of the model parameters.
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In-mine Geoelectric Methods for Detection of Tectonic Disturbances of Coal Seams
Authors T. Ormos, Á. Gyulai and M. DobrókaIn-mine geoelectric methods - the geoelectric seam-sounding and geoelectric transillumination - were
applied for detection of fault zones in a coal mine. The measured data were interpreted using geoelectric
tomography algorithm. Appreciable agreements were found between the location of tectonic zones
predicted by the interpretation and those observed during the mining extraction.
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Rayleigh wave modeling in laterally inhomogeneous media with subsurface anomalies
Authors S. Sharma, S. Butt and P. BordingThe inversion of Rayleigh wave dispersion curves can yield the shear wave velocity profile which
gives the image of subsurface. In most of the existing techniques of computing Rayleigh wave dispersion
curves, it is assumed that the subsurface consists of horizontally flat layers.
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3-D MASW
Authors C. Park and M. CarnevaleBecause MASW analysis focuses on the inline propagation of planar surface waves in its data
acquisition with linear receiver array and then in the subsequent dispersion imaging process, the useful
outcome of 2-D shear-wave velocity (Vs) mapping best represents the cross sectional image of the
subsurface below the survey line with minimal influence from the offline features like side scattering.
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MASW Survey Using Multiple Source Offsets
Authors C. Park and J.B. ShawverAlthough it is generally known that the active MASW method tends to average out the near-field
effect of surface waves through the slant-stack process implicitly incorporated in dispersion imaging and
therefore one optimum source offset (X1) is usually employed for a given survey, a long source offset to
ensure recording of long wavelengths can sometimes result in a lack of short-wavelength energy due to
excessive attenuation and, on the other hand, the use of a short source offset can result in the opposite
consequence.
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Misleading Interpretation of Shallow Seismic Methods: Three Case Studies from MASW, P-wave Reflection and S-wave Reflection Surveys
Authors A. Ismail, Y. Kontar, E. Smith, A. Philips and A. StumpfDespite the reliable performance of high resolution seismic methods for imaging the shallow subsurface, in some cases interpreting seismic results can be misleading. We present three case studies where results from, P-wave reflection, SH-wave reflection, and MASW surveys were incorrectly interpreted because of inadequate constrains on either the surface or subsurface conditions of surveyed sites.
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A trade-off solution of regularized geophysical inversion using model resolution and covariance matrices
More LessRegularization is necessary for inversion of ill-posed geophysical problems. Appraisal of inverse
models is essential to a meaningful interpretation of these models. Because uncertainties are associated
with regularization parameters, extra conditions are usually required to determine proper parameters for
assessing inverse models.
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Robust and Broadband Finite Difference, Time Domain GPR Modeling - Keynote Session
Authors J. Daniels, R. Lee, Y.C. Yi, R. Ortega and K. ShalekThree dimensional finite difference time domain modeling (FDTD) has been used for many years in engineering and Earth science applications. The earlier versions were fraught with problems and limitations, including an inability to be used for modeling a broad range of frequencies, difficulty modeling large physical property contrasts between grid cells, and no ability to vary the grid size within the model.
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Broadband Finite Difference Time Domain Modeling
Authors J. Daniels, R. Lee, Y.C. Yi, R. Ortega and K. ShalekCode was designed at The Ohio State University Department of Electrical and Computer Engineering in conjunction with the School of Earth Sciences with the goal of forward modeling subsurface geological systems. To attain this goal the finite difference time domain (FDTD) method was implemented through single- and multi-processor systems leading to the name parallel finite difference time domain (PFDTD).
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Estimating Debye Parameters from GPR Reflection Data Using Spectral Ratios
Authors J. BradfordIn the GPR frequency range, electromagnetic wave attenuation is largely controlled by dielectric
relaxation processes. A primary relaxation commonly occurs in the 10 – 100 MHz range for many
earth materials in which the GPR signal propagates effectively. This relaxation leads to strong nonlinearity
in the frequency dependent attenuation and occurs in a frequency range that is often used for
groundwater investigations.
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Fracture Pattern Delineation Using Seismic Attribute Algorithms in s 3D GPR Data Set
Authors O. Davogustto, R.A. Young and I. CemenFractures are caused by changes in stress patterns. Fracture delineation using geophysical
techniques allows for a better understanding of stress processes and fluid flow. The main objective of
this study is to delineate and map fractures in a granitic body with the help of attribute algorithms. The
data is a 3D GPR survey consisting of 24 parallel lines on the Tishomingo Anticline in southern
Oklahoma. Changes in the dielectric constant between the granite and the fracture fill (air or water) will
produce a distinctive amplitude response related to geological features characteristic of the fractures.
Amplitude attribute algorithms allow the identification of fracture patterns. The resulting fracture
interpretation is corroborated by the surface fracture data.
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Application of the Mean Traveltime Curves to GPR and VSP Data
Authors J.L. Fernández Martínez, L.M.P. González, J. Deparis, M.D. Mangriotis and J.W. RectorAcoustic tomography methods belong to the class of non destructive inspection techniques and
are widely used in engineering applications. One of the main issues for these methods is the direct
arrivals, which can be noisy or affected by scattering or other propagation effects.
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Geophysics in the Search for Homer's Ithaca - Keynote Session
Authors G. Hodges, D. Kilcoyne, R. Eddies and J.R. UnderhillIdentifying the location of the island of Ithaca, legendary home of Odysseus, has been a problem
for historians for centuries. The modern island of Ithaki, in the Ionian Sea, does not match the
description in Homer’s epic poem. In 2003 Robert Bittlestone initiated a study of the Paliki peninsula in
western Cephalonia in an attempt to determine whether this was the island that Homer called Ithaca,
then separated from the rest of Cephalonia by a sea channel later described by the Greek geographer
Strabo.
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Applications of Geophysics to Archaeology: Magnetic and Ground-Penetrating Radar Investigation at Hatshepsut Temple, Luxor, Egypt
Authors H. Odah, A. Ismail, I. Elhemaly, A. Abbas and F. ShaabanHatshepsut Temple, built on the western bank of Luxor during the Eighteenth Dynasty, is one of the most magnificently preserved royal mortuary temples in the world. The temple’s first court (60 m x 100 m), which is currently covered by dry sands, has been described by archeologists as a vast garden that contained special plants and trees brought by Queen Hatshepsut from Africa. This garden linked the temple to the Nile Valley by an avenue of sphinxes.
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A Geoarcheological Investigation in Medieval Coastal Dunes using Ground-Penetrating Radar
Authors M. Bakker, P. Vos, S. de Vries and P. DoornenbalIn the sea harbor of IJmuiden, the Netherlands, a sandy island was removed. In the light of high
archeological expectance a geoarcheological inventory was compulsory prior to the digging and
dredging. Prospective geoarcheological research in aeolian environments concerns a standard procedure
involving the determination of paleosols by borings. The paleosols were found at the site obliging
digging of an inventory trench. Before the trenching a 100 MHz ground-penetrating radar (GPR) survey
was conducted yielding a penetration depth of about 6 to 7 m. Rationale was to deduce the suitability of
GPR for prospecting geoarcheological research in coastal dunes. Radar facies units were compared with
observations in the trench. Furthermore, 14C and OSL dating of molluscs and sediments was done.
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Preliminary Archaeological Geophysics Results at Fort Garland
Authors R. North, T. Goddard and R. GoddardAdams State College has conducted its archaeology field school at Fort Garland, CO for the last
six years. A focus of the field work for the last two years has been the parade ground, which is a grass
covered field approximately 50 by 75 meters.
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Correlating Helicopter EM and Borings for Levee Evaluation Studies in California
Authors D. Amine, G. Hodges, S. Selvamohan and D. MarlowOn-going studies of the flood-control levees in the Sacramento valley, California have included airborne EM and magnetic surveys, DC resistivity surveys, cone penetrometer testing and reverse-circulation borings. This paper reports on how airborne EM is being used to provide a regional overview of the levee foundations, tie-together and extend the CPT and boring information, as well as providing mapping of the horizontal extent of sand channels.
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Synergistic Geophysical Techniques for Assessing Seepage Pathways in Earthen Levees
Authors M. Miele, T. Dobecki, J. Flemmer, M. Lightner and S. TakataThe Sacramento River Delta is the second largest river delta in the United States. Many
hundreds of miles of earthen levees were built in the early 1800's and were not built to today’s
engineering standards. At the time, local earthen materials were used to build the levees resulting in a
wide range of materials and related conditions. Therefore, the levees are prone to breaching, failure,
and/or other catastrophic events (past events have occurred).
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