GPR Survey Research Articles

Application of 1-D Convolutional Modeling to Interpretation of Ground Penetrating Radar Profiles-Turbidite Channel Sandstone 1, Lewis Shale, Wyoming

Complex stratigraphic relationships, distinct lithologic facies, and variable bed thickness characterize channel-levee elements of turbidite sections examined in outcrop. The 3-D configuration of these features in the subsurface cannot be determined accurately using only logs in sparsely distributed and unevenly spaced boreholes. The missing interborehole information can be filled in by three-dimensional GPR surveys so long as the geological elements can be recognized in the data. This recognition can be aided by 1-D convolutional waveform modeling, which is able to separate multiples and refracted events from primary reflections, to predict severe amplitude loss due to attenuation in shales, to constrain reflection polarities and traveltimes, and to elucidate the role of interference within thin sandstone beds. Two-dimensional GPR profiles and a 3-D GPR survey image the lowermost and largest of a series of laterally offset, vertically stacked channel sandstones of the Lewis Shale, near Dad, WY. We combine measured sections, borehole logs, and cuttings to form a one-dimensional, blocked framework into which are embedded the laboratory-measured electrical properties of four facies. Zero-offset, non-dispersive impulse responses are computed and convolved with the waveform used in the surveys to produce synthetic radargrams. Modeling applies a frequency-independent attenuation and includes multiples up to second order. These synthetics are compared to nearby GPR sections that have been datum static-corrected using differential GPS elevations. The present modeling makes possible the interpretation of four features of major geological significance—the base of channel, the top of a shale-clast conglomerate, a featureless sandstone, and eroded channel∕levee mounds (erosional remnants). This case history shows that the use of 1-D models can reveal internal consistency among geological mapping, borehole information, laboratory measurements, and radar stratigraphy.

Assessment of Pollution Near Landfill Site in Nagpur, India by Resistivity Imaging and GPR

Groundwater pollution in the vicinity of a landfill site in Nagpur, India is assessed with the help of resistivity imaging and GPR tools. The resistivity imaging survey indicates high conductive anomalies in the topsoil as well as the underlying fractured rocks. Significant reflections from the GPR records known as radargrams are extracted with the help of maximum peak module and Hilbert transform module in RADAN 6. These reflections can be attributed to presence of fractures, which are potential pathways for migration of the fluid. The geophysical findings are strengthened by the results of groundwater analysis from wells located close to the profile where resistivity and GPR survey have been carried out. The study has indicated the vulnerability of the unconfined aquifer underlying the predominantly clay layer.

Geological Characterization of the Idalia Hill Fault Zone and Its Structural Association with the Commerce Geophysical Lineament, Idalia, Missouri

The Commerce geophysical lineament (cgl) is a 600-km-long, 5- to 10-km-wide, northeast-trending magnetic and gravity anomaly that extends from northeastern Arkansas to central Indiana. The seismogenic potential of the cgl is poorly known. However, recent geologic and geophysical studies along faults overlying the cgl support the notion that this prominent geophysical anomaly may be a source of future large-magnitude earthquakes in the central United States. Our geomorphic mapping, acquisition of seismic reflection, and ground-penetrating radar data, coupled with paleoseismic trenching and borehole information, collected at the South Holly Ridge site, near Idalia, Missouri, provide evidence of late Pleistocene to early Holocene deformation on the Idalia Hill fault zone. The Idalia Hill fault is a 0.5-km-wide zone of northeast-striking, near-vertical faults that directly overlie the cgl and coincide with the southeastern margin of the Bloomfield Hills. At the South Holly Ridge site, fault-related geomorphic features include a prominent, northeast- trending linear trough bounded on the southeast by a 2- to 3-m-high linear, north- facing escarpment and an apparent right-laterally deflected creek. These features, in turn, are aligned with regional northeast-trending linear valleys, escarpments, linear and deflected drainages, springs and bedrock notches mapped northeast and southwest of the site. Seismic reflection data across the Idalia Hill fault zone image near- vertical faults that displace Tertiary/Cretaceous and Tertiary/Quaternary reflectors and project upward to faults interpreted from ground-penetrating radar (gpr) surveys, and trench exposures. Together, these results suggest that deformation at the site is coincident with the cgl and is of primary tectonic origin. Trenches excavated across the linear escarpment at the South Holly Ridge site expose faulted and warped Tertiary deposits, Pleistocene gravel (reworked Mounds Gravel), the Sangamon Geosol, late Pleistocene Peoria Loess, and a late Pleistocene to early Holocene paleosol. Analyses of trench, borehole, and gpr data constrain the timing of the most recent event on the Idalia Hill fault to between the latest Pleistocene (about 18 ka) and early Holocene (pre-7.7 ka). Evidence for a penultimate event predates 23 to 18 ka. The timing of these events overlaps with late Pleistocene to early Holocene faulting and paleoliquefaction events evaluated elsewhere on northeast-striking faults overlying the cgl in southeastern Missouri. The earthquake- timing data from these sites in southeast Missouri indicate that the Commerce section of the cgl acted as a seismogenic source into at least the early Holocene and thus should be considered in future seismic-hazard analysis of the central United States.

Insights into the use of time-lapse GPR data as observations for inverse multiphase flow simulations of DNAPL migration

Perchloroethylene (PCE) saturations determined from GPR surveys were used as observations for inversion of multiphase flow simulations of a PCE injection experiment (Borden 9 m cell), allowing for the estimation of optimal bulk intrinsic permeability values. The resulting fit statistics and analysis of residuals (observed minus simulated PCE saturations) were used to improve the conceptual model. These improvements included adjustment of the elevation of a permeability contrast, use of the van Genuchten versus Brooks–Corey capillary pressure–saturation curve, and a weighting scheme to account for greater measurement error with larger saturation values. A limitation in determining PCE saturations through one-dimensional GPR modeling is non-uniqueness when multiple GPR parameters are unknown (i.e., permittivity, depth, and gain function). Site knowledge, fixing the gain function, and multiphase flow simulations assisted in evaluating non-unique conceptual models of PCE saturation, where depth and layering were reinterpreted to provide alternate conceptual models. Remaining bias in the residuals is attributed to the violation of assumptions in the one-dimensional GPR interpretation (which assumes flat, infinite, horizontal layering) resulting from multidimensional influences that were not included in the conceptual model. While the limitations and errors in using GPR data as observations for inverse multiphase flow simulations are frustrating and difficult to quantify, simulation results indicate that the error and bias in the PCE saturation values are small enough to still provide reasonable optimal permeability values. The effort to improve model fit and reduce residual bias decreases simulation error even for an inversion based on biased observations and provides insight into alternate GPR data interpretations. Thus, this effort is warranted and provides information on bias in the observation data when this bias is otherwise difficult to assess.

Fracture orientation determination in sedimentary rocks using multicomponent ground-penetrating radar measurements

The resolution provided by conventional single-component GPR surveys is not always sufficient to determine fracture location and orientation. Multicomponent measurements can help in these determinations through phase and amplitude analysis. The phase of a radar wavelet is altered as it passes through a fracture. The amount of phase change depends upon the relative orientation of the fracture and the direction of the incident electric field. If the phase change is measured for a known orientation of the antennas, then the strike of the fracture can be determined. For our purpose, multicomponent means repeating measurements at the same location for different antenna configurations and orientations.

Análise do emprego do GPR para estimar o teor de umidade do solo a partir de um estudo na cidade de São Paulo

Este trabalho apresenta resultados de estudos visando a estimativa dos teores de umidade de solos superficiais com GPR em uma area teste na cidade de Sao Paulo/SP, Brasil, e a analise da acuracia dos processos envolvidos. Foram empregadas duas metodologias diferentes: i) ajuste linear dos tempos de chegada da onda direta no solo para diferentes afastamentos; ii) diferencas dos tempos de chegada da onda aerea e da onda direta no solo para um unico afastamento. Utilizamos o equipamento da RAMAC Mala Geosciences com antenas de 50 MHz, 100 MHz e 200 MHz. A aquisicao constituiu-se de diversos perfis multi-offset (multiplos afastamentos) com o emprego da geometria WARR (Wide Angle Reflection and Refraction ) ao longo de um perfil em tres periodos climaticos distintos (seco, intermediario e umido). Sendo o incremento entre os tracos dos perfis multi-offset 0,2 m para a antena de 50 MHz e 0,1 m para as antenas de 100 MHz e 200 MHz. Concomitantemente ao levantamento GPR foram coletadas amostras de solo a intervalos de 0,5 m desde a superficie do terreno ate a profundidade aproximada de 4,0 m para a determinacao de seus teores de umidade em laboratorio. Os resultados do GPR apresentaram boa correlacao com os dados obtidos atraves das analises de laboratorio, sendo que os obtidos com as antenas de frequencia central de 200 MHz propiciaram os melhores resultados. Os dois metodos empregados apresentaram diferentes acuracias. O metodo da diferenca dos tempos de chegada da onda aerea e da onda direta no solo foi o menos preciso devido a ocorrencia de um deslocamento de tempo da reta de ajuste dos tempos de chegada da onda direta no solo no afastamento zero. Esses resultados mostraram que, nesses casos, e importante aplicar um fator de correcao para melhorar a acuracia dos resultados finais.

Phased-array transmitters for GPR surveys

The antennas commonly used in ground penetrating radar surveys have wide illumination, but limited spatial resolution. To overcome this limitation, we propose the use of phased-array transmitters, which allow us to direct the electromagnetic energy. We first perform a theoretical analysis to determine the influence of the number of antennas, the antenna spacing and the phase shifts between antennas. This analysis is useful to define the direction of the main lobe of the radiation pattern and its width. The simulations, which show the versatility of using phased arrays as compared to a single antenna, have been done to determine the best array parameters to image a given interface. On the basis of these simulations, we acquired common-receiver gathers with two single 100 MHz antennas to simulate a single survey involving 21 phase-shifted transmitter antennas and a single-receiver antenna. We have improved the signal-to-noise ratio, and the lateral coherence of the reflection events, and obtained a greater penetration depth as a consequence of the energy focusing.

Contribution of geophysics to outlining the foundation structure of the Islamic Museum, Cairo, Egypt

AbstractThe Islamic museum was erected in 1896. The building is situated in the heart of Cairo (capital of Egypt) and holds marvellous Islamic antiquities and priceless ancient hand‐writing and rare books. Recently, a restoration scheme has been planned to secure the old building which suffers from weakened foundations. In addition, the wooden roofs will be replaced by concrete ones and an extra floor will be integrated into the building. Unfortunately, the architecture construction charts were neither available nor obtainable. Therefore, the structure of the foundations and the base walls of the building had to be outlined. At the time of construction, three major fundamental wall designs were dominant and were to be considered during the work approach.Ground‐penetrating radar (GPR) and dipole–dipole resistivity imaging have been integrated to (define the structure of the foundation walls of the building. A Ramac2 system connected to a 500 MHz antenna has been utilized for conducting the GPR survey. In addition, a Terrameter SAS 1000 single channel device has been used for performing the resistivity profiles. At accessible spaces around the building GPR and resistivity profiles were obtained. The GPR analysis has revealed the depth of the foundation walls to be about 0.9 m from the ground surface with a width close to 0.6 m. The wall design is close to a straight wall style. Furthermore, the analysis of the dipole–dipole resistivity measurements has matched the geology of the area, where subsoil anomalies may be due to the scattered limestone blocks that occur in the area. Moreover, the foundation walls have resistivity values that fall into the range of fractured limestone or limestone blocks. A step‐wise or inclined foundation wall style has not been indicated through the parallel resistivity profiles. Copyright © 2005 John Wiley & Sons, Ltd.

Interpreting DNAPL saturations in a laboratory‐scale injection using one‐ and two‐dimensional modeling of GPR data

AbstractGround‐penetrating radar (GPR) is used to track a dense non–aqueous phase liquid (DNAPL) injection in a laboratory sand tank. Before modeling, the GPR data provide a qualitative image of DNAPL saturation and movement. One‐dimensional (1D) GPR modeling provides a quantitative interpretation of DNAPL volume within a given thickness during and after the injection. DNAPL saturation in sublayers of a specified thickness could not be quantified because calibration of the 1D GPR model is nonunique when both permittivity and depth of multiple layers are unknown. One‐dimensional GPR modeling of the sand tank indicates geometric interferences in a small portion of the tank. These influences are removed from the interpretation using an alternate matching target. Two‐dimensional (2D) GPR modeling provides a qualitative interpretation of the DNAPL distribution through pattern matching and tests for possible 2D influences that are not accounted for in the 1D GPR modeling. Accurate quantitative interpretation of DNAPL volumes using GPR modeling requires (1) identification of a suitable target that produces a strong reflection and is not subject to any geometric interference; (2) knowledge of the exact depth of that target; and (3) use of two‐way radar‐wave travel times through the medium to the target to determine the permittivity of the intervening material, which eliminates reliance on signal amplitude. With geologic conditions that are suitable for GPR surveys (i.e., shallow depths, low electrical conductivities, and a known reflective target), the procedures in this laboratory study can be adapted to a field site to delineate shallow DNAPL source zones.

P-37 六甲山地,五助橋断層帯の地中レーダ探査(9. 地域地質・地域層序)

P-37 六甲山地,五助橋断層帯の地中レーダ探査(9. 地域地質・地域層序)

A Radar Survey at a Granite Quarry to Delineate Fractures and Estimate Fracture Density

Borehole radar, both reflection and tomography methods, and GPR surveys were conducted at a granite quarry to delineate rock inhomogeneities, including major fractures, and to estimate the fracture density. The borehole reflection survey used a directional antenna to get the spatial orientations of the reflectors. The center frequency was [Formula: see text] for the borehole radar reflection and tomography surveys and [Formula: see text] for GPR. Through the interpretation of borehole reflection data using dipole and directional antennas, as well as surface GPR images, we could determine the orientation of the major fractures in three dimensions. Portions of the tomography travel time curves exhibited velocity anisotropy, which is uncommon in granite. Comparing the tomography data with Televiewer images showed that the anisotropy effect in this area is closely related to the alignment of fine fissures. From the borehole radar, tomography, and GPR images as well as the distribution of anisotropy, we conclude that the area bounded by the two fractures, MF2 and MF5, has the freshest granite in the surveyed area. This case study demonstrates that a combination of surface, borehole reflection, and tomographic radar surveys can provide the three-dimensional distribution of major fractures and an estimate of fracture density.

Discovery of a 1st Century AD Roman Amphitheater and Other Structures at the Forum Novum by GPR

A Roman marketplace and town called the Forum Novum, initially began construction in the [Formula: see text] century BC and flourished well into the [Formula: see text] century AD. At present most of the town remains is below ground. The site is situated next to a completely restored [Formula: see text] century AD church and a partially reconstructed marketplace. Ground penetrating radar surveys have been conducted at the Forum Novum during 1998 through 2001 field seasons to remotely detect buildings of this ancient town. Using 300 and [Formula: see text] radar antennas and closely spaced radar profiles, time slice and 3-D volume analysis of the reflection data were computed. GPR surveys in the area detected a large oval-shaped structure [Formula: see text] along its major axis. This structure is from a [Formula: see text] century AD Roman amphitheater. Subsequent excavations from one of the eight entrances reveal that the internal amphitheater oval is nearly a meter thick and is composed of a cemented stone wall buried [Formula: see text] below the ground surface. The time slices revealed completely different top layer reflections from structures associated with a destroyed mausoleum, which could also be seen by the naked eye as crop marks. Archaeologists often reconstruct subsurface archaeology based on crop marks. In this case however, radar was able to detect structures near the surface—and a much different set of structures lying deeper using time slice analysis. Other structures detected in the GPR surveys include a large building complex found next to a reconstructed marketplace, and believed to be living quarters adjacent to the central market area. A large Roman villa was also imaged in one area and later excavated to reveal internal walls that include a garden atrium.

A comparison of segmentation techniques for target extraction in ground‐penetrating radar data

ABSTRACTIn a typical GPR survey, only a small fraction of the collected data actually represent useful data (i.e. target data), whereas the majority of the data is considered redundant. The first of the post‐processing stages, which relies heavily on a skilled operator, involves indicating those areas that may contain targets and suppressing others. Consequently, this process consumes considerable amounts of time and effort, apart from the fact that the existence of the human factor at this critical stage invariably introduces inconsistency and error into the interpretation. In this paper, automatic detection and segmentation techniques for GPR data are discussed and compared. The techniques rely on the computation of certain features from which a neural network is then able to arrive at a decision whether to classify the data segments in question as targets or otherwise. The first technique is based on extracting statistical features from A‐scan segments while the second technique computes statistical features from B‐scan regions. In the third technique, some regional properties of B‐scan segments are used to achieve discrimination not only between targets and non‐targets, but also between hyperbolic‐shaped and non‐hyperbolic‐shaped targets. All the techniques were tested on different types of GPR data collected from a variety of sites, and they proved to be very efficient in forming a robust automatic technique for data reduction and segmentation. In addition, these techniques are carried out in near real‐time enabling on‐site processing and interpretation of collected data.

4-D ground penetrating radar monitoring of a hydrocarbon leakage site in Fortaleza (Brazil) during its remediation process: a case history

A 4-D monitoring GPR survey was carried out in order to outline the light non-aqueous phase liquid (LNAPL) plume underground during a remediation process in the area of an impacted gas station in Fortaleza, NE Brazil. The complex GPR signature of the plume was well characterized. Low reflectivity zone corresponds to hydrocarbon vapor phase in the vadose zone. Enhanced reflections are associated with free and residual products directly above the water table. A theoretical model based on geochemical zonation of the LNAPL was calculated using a finite difference time domain (FDTD) forward modeling code, whose synthetic radargrams provide useful insight into the nature of the reflection events related to LNAPL contamination. Hydrogeologic and hydrochemical data from installed monitoring wells provided additional support for interpreting of the GPR response. Moreover, a network of radar sections collected during fifteen months at the polluted site show clearly temporal changes in the plume dimensions, induced by regular pumping of groundwater. This corrective action caused an important drop of the water table that was followed by a rapid shrinking of the impacted area in the vadose zone, generating pooling of vapor products. A steady restore of the reflectivity in the shadow zone suggests a decrease of LNAPL saturation along the GPR survey.

Geophysical study of a palaeofualt scarp near Hyden, Western Australia

Fault scarps created by prehistoric seismic events are potentially important source of information for seismic-hazard assessment. Establishing the type of faulting responsible for the scarp and its structural setting allows other earthquake prone areas to be identified. Dating the scarp, along with estimates of the magnitude of the event responsible for its formation based on accurate mapping of the structure, allow recurrence intervals to be estimated. Aeromagnetic data flown over a fault scarp at Hyden allow the geological structures reactivated in the scarp-forming events to be identified. At Hyden thrust faulting occurred on a pre-existing structure, one of several similar structures in the area. A GPR survey allows sedimentary materials deposited adjacent to the scarp to be located in the subsurface. Dating of these materials will allow the age of the scarp-forming event to be established.

Multidimensional prospecting in North American Great Plains village sites

AbstractGeophysical survey results are described for four prehistoric and historic fortified earthlodge settlements located in the Middle Missouri River basin of North and South Dakota, USA. One impetus for this work is the upcoming bicentennial of the Lewis and Clark expedition of 1804–1806 that used the Missouri as its route of travel. Celebrated as an event that helped to open the American West to Euroamerican settlement, tourism at archaeological parks is expected to markedly increase. Multidimensional geophysical surveys were used to pin‐point cultural anomalies for archaeological excavation and interpretation, but more importantly, the wide‐area mapping of the subsurface at these villages allowed visualization of their structure and organization, yielding many new insights. At Menoken Village (AD 1240) previously unknown houses, oval in form, were revealed magnetically owing to their intense burning, as was an intravillage trail system seen in resistivity data. At Whistling Elk Village (AD 1300) the first glimpse of the nature of this deeply buried settlement was achieved by resistivity and conductivity surveys, with magnetic indications that half of the houses had been burned. The geophysical evidence also hints at a second village, much more compact, that may lie within the primary settlement, supporting an attack theory established by limited excavation evidence. At Huff Village (AD 1450) the magnetometry survey revealed the presence of vast numbers of previously unsuspected food storage pits outside of the numerous dwellings that lie within this settlement. At Mitu'tahakto's (1822–1861), an early historic Mandan/Arikara settlement, resistivity and GPR surveys discovered the presence of new and overlapping houses, and magnetometry indicated large differences in the number of iron artefacts between households, pointing to possible variations in access or status. Copyright © 2003 John Wiley & Sons, Ltd.

Integrated signal enhancements in magnetic investigation in archaeology

The magnetic method can be efficiently applied to archaeological investigation especially when the S/N ratio is enhanced appropriately. This study presents a model experiment and field examples of magnetic exploration in archaeology. By using appropriate measuring processes and filtering methods, the conventional and more recent magnetic prospecting techniques are successfully applied to the very shallow, small-scale investigations, which are used to locate and map archaeological targets. We focus on mapping the buried slate caskets in the alluvial environment, which is the most commonly encountered and readily preserved ones at the archaeological sites of Taiwan. The gradiometry and the inferred derivatives may resolve individual anomalies. Locations of the maxima determined by the 3-D analytic signals can be used to describe the outlines of the bodies that cause the anomalies. Furthermore, the susceptibility was very successful in mapping near-surface targets at the Chubin site. The magnetic results of the example at the Hutzushan site, compared to the GPR survey carried out by previous investigators, indicate that the GPR anomalies may be caused by other sources. The magnetic response of a casket can be displayed in various ways, depending on the pole distribution of the casket, the geometry, the magnetization direction and the orientation of buried casket. The processing methods may improve the data resolution, but precautions must be taken for the artifacts.

Improved Three-Dimensional Image Reconstruction Technique for Multi-Component Ground Penetrating Radar Data

For electromagnetic imaging the vectorial character of the emitted field and the radiation characteristics of both source and receiver play an important role. Recently, a new imaging algorithm was presented dedicated to the electromagnetic case. The radiation characteristics of GPR source and receiver antennas and the vectorial nature of the electromagnetic waves are taken into account for a monostatic fixed offset GPR survey. This resulted in a representative image of a point scatterer. Comparison with scalar imaging algorithms shows that for a homogeneous space the SAR image has an opposite sign compared to the multi-component image, whereas the Gazdag image has a phase shift of about 90° with respect to the multi-component image. In this paper, modified scalar imaging algorithms are introduced that minimize these differences. However, between the images obtained in a homogeneous half-space phase differences of 10–20° are still present. These differences indicate the possible error in nature of the physical property contrast when it is determined with the modified scalar imaging algorithms. The multi-component imaging algorithm returns a representative image because it uses the appropriate Greens functions to eliminate the propagation effects. For practical imaging strategies, only far-field radiation characteristics can be used to compensate for the propagation effects due to the large computing time needed to evaluate the total-field expressions. Synthetic analysis of the imaging of a point scatterer calculated using total-field expressions shows that using the far-field expressions in the multi-component imaging algorithm the images better approximate the actual contrast than using the modified scalar imaging algorithms. Experimental results are presented from imaging several buried objects with different medium properties and different orientations. The phase differences in the experimental data are similar to those obtained synthetically. This likeness indicates that using the multi-component imaging algorithm, a more reliable image is obtained than with the modified scalar imaging algorithms.

The use and application of GPR in sandy fluvial environments: methodological considerations

Abstract Ground penetrating radar (GPR) is a popular technique for imaging and interpreting sedimentary architecture. However, current literature shows a wide range in the quality of information provided on the GPR methodology and processing technique. It is therefore difficult to judge the validity of the GPR interpretations and this produces inherent difficulties for comparison between surveys. This paper describes the key steps required to collect, process and interpret GPR surveys in sandy fluvial sediments. GPR data from the South Saskatchewan River, Canada, are used to illustrate each stage of data collection and processing. Particular attention is given to the appropriate set-up conditions for the GPR software and hardware, the selection of data-processing techniques and velocity analysis. Methods for the interpretation of GPR reflectors are also investigated using ground-truth control provided by a cut-face exposure. This paper presents recommendations for a systematic and rigorous methodology for the collection, processing and interpretation of GPR data in sandy fluvial environments. The paper suggests that all data-collection parameters and processing steps should be recorded or tabulated in any GPR publication to facilitate comparisons between surveys.

Influence of antenna configurations for GPR survey: information from polarization and amplitude versus offset measurements

Abstract Ground penetrating radar (GPR) images depend strongly on the relative geometry between the transmitter, the receiver and the subsurface reflectors. This dependence results from the directional properties of the antennae and from the sensitivity of the reflector to the polarization of the incident electromagnetic wave. In the present study, GPR data sets have been recorded using several 100 MHz antennae configurations, including transverse electric (TE) or transverse magnetic (TM) modes that have been used both parallel and perpendicular to the recording line. The images obtained show a high complementarity that provides more detailed information of the studied geological reflectors compared to the image derived from a single conventional acquisition configuration. Consequently, we compute pseudoprofiles that gather information derived from all acquisition modes, thus improving the GPR images. These pseudo-profiles are characterized by either a low directional degree of the antennae or a neutral acquisition mode. In addition, we have conducted a polarization analysis by surveying the studied profile twice with parallel and perpendicular antennae, in both modes (TE and TM). The comparison of these data sets provided three-dimensional (3-D) information on reflectors, particularly their depolarization properties. These studies clearly emphasize how multiconfiguration antennae surveys have the potential to improve GPR imaging and interpretation. Furthermore, polarimetric surveys have been carried out in order to explore further whether depolarization phenomena could explain observations of phase inversion and amplitude decrease on TE common mid-point gathers that would induce perturbations of the GPR images in the stacking procedure for multi-offset surveys.