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Near Surface 2004 - 10th EAGE European Meeting of Environmental and Engineering Geophysics
- Conference date: 06 Sep 2004 - 09 Sep 2004
- Location: Utrecht, Netherlands
- Published: 06 September 2004
21 - 40 of 132 results
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Cross-Borehole Resistivity Tomography below Foundations in Covered Karst
Authors J. Deceuster, J. Delgranche and O. KaufmannA021 CROSS-BOREHOLE RESISTIVITY TOMOGRAPHY BELOW FOUNDATIONS IN COVERED KARST AUTHORS Abstract 1 This paper presents a case study conducted below building foundations in a karstic area at Tournai (Belgium). Geophysical investigations were carried out to map the complex geometry of the subsurface. Twenty-three cross-borehole resistivity panels with multiple arrays were performed on the site. Data were inverted with Res2DInv ® software. Tomographies give a good overview of the competent bedrock geometry and also allow to delineating covered weathered limestone. Introduction The investigated building is situated at Tournai in the south-west of Belgium. Several collapses from 2 to 3 meters in
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High Resolution Seismic Experiment within the Low-Noise Underground Laboratory (LSBB) of Rustrel (Province)
Authors G. Sénéchal, D. Rousset, E. Gloaguen and T. LebourgA022 High resolution seismic experiment within the low-noise underground laboratory (LSBB) of Rustrel (Provence). Abstract (1) (1) (2) (3) GUY SÉNÉCHAL DOMINIQUE ROUSSET ERWAN GLOAGUEN AND THOMAS LEBOURG (1) FRE 2639 – Imagerie Géophysique Pau – IPRA Université de Pau et des Pays de l'Adour - 64000 Pau – France (2) Dép. Des Génies Civil Géologiques et des Mines – École Polytechnique de Montréal - Montréal C.P.6079 – Canada 1 (3) UMR 6526 - Géosciences Azur – Sophia Antipolis 06560 Valbonne – France Several high resolution seismic experiments have been performed along underground galleries located 200 meters below the surface.
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Advances in the Interpretation of Geophysical Borehole Logs
Authors M.G.G. de Jong, S.D. Nio, D.T. Biewinga and D.G. SmithA023 ADVANCES IN THE INTERPRETATION OF GEOPHYSICAL BOREHOLE LOGS Summary 1 Modern software packages greatly facilitate the analysis and interpretation of geophysical borehole logs. Standard applications in hydrogeology and petroleum geology such as the evaluation of lithology and reservoir fluids are nowadays carried out routinely with such software. A disadvantage of most packages is that they are developed for the experienced geophysicist. Software tailored to the needs of geologists and hydrologists is now also available. Using flexible scaling options histograms and advanced multiple log display functions the non-petrophysicist can quickly evaluate lithological parameters and the nature of the fluids in
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Random Gridding Decomposition (RGD) in Seismic Tomography
By B. AbbadA024 RANDOM GRIDDING DECOMPOSITION (RGD) IN SEISMIC TOMOGRAPHY Abstract 1 The purpose of this work is to invert crosswell first arrival data on a high resolution velocity grid called the fundamental grid obtained by running several tomographic inversions on grids of smaller size generated randomly. Later the inversion results of these grids are scaled by the ray density and the pixel area to produce a final velocity image with a better resolution. The method has proven a significant gain in computing time for the inversion and has given superior results than those provided using simple grids of similar size especially
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Integrated GPR and Geo-Resistivity Study of Shallow Stratigraphy in Sandy Coastal Environments
Authors M. Pipan, E. Forte, M. Sugan, G. Dal Moro and P. GabrielliA025 INTEGRATED GPR AND RESISTIVITY STUDY OF SHALLOW STRATIGRAPHY IN SANDY COASTAL ENVIRONMENTS Abstract 1 We performed an integrated Multi-Fold GPR and resistivity survey in a coastal area in the northern part of Italy (Adriatic coast) to reconstruct 3D stratigraphy to localize vadose zone and water table and to identify possible man-made structures and excavations. The spatial sampling was sufficiently dense to perform 3-D interpretation of radar data and 2.5-D reconstruction of iso-resistivity surfaces across the grid. Processing of GPR Single and Multi Fold data focused on true amplitude signal recovery in order to preserve information related to electromagnetic impedance
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Soil Moisture Dynamics with Time Lapse GPR
Authors J. Schmalholz, A. Kemna, M. Müller, H. Stoffegen and U. YaramanciA026 SOIL MOISTURE DYNAMICS WITH TIME LAPSE GPR J. SCHMALHOLZ 1 A. KEMNA 2 M. MÜLLER 1 H. STOFFEGEN 3 AND U. YARAMANCI 1 Introduction 1 Tracing the water content in the uppermost soil is of great interest for a variety of different scientific disciplines. Since many processes are linked to the volumetric water content and its dynamics the scale of interest ranges from kilometres to submetres. With the availability of shielded high frequency ground penetrating radar (GPR) antennas a non- respectively minimally invasive geophysical tool valuable information concerning the water content can be obtained with a spatial resolution in
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Monitoring of Water Infiltration Using GPR Data
Authors P. de Beukelaar, S. Mazouz, M. Meinster, A. Saintenoy and P. TucholkaA027 Monitoring of water infiltration using GPR data Summary A Ground Penetrating Radar survey was carried out for water infiltration monitoring and mapping of shallow subsurface conditions. A first measurement allowed high resolution mapping of subsurface conditions and assessment in variations of the GPR reflection response for saline water infiltration in the upper few metres of unsaturated soil. In total three sites with representative lithologies of the Paris Basin were investigated to compare hydrologic behaviour in different types of soil. This paper shows results from both synthetic modelling as well as from measurements carried out over sands nearby Rambouillet. Further
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Fracture Characterisation Using the NA Inversion Algorithm on Synthetic GPR Signals
Authors C. Gregoire, M. Jeannin, M. Wathelet, S. Garambois and D. JongmansA028 FRACTURE CHARACTERISATION USING THE NA INVERSION ALGORITHM ON SYNTHETIC GPR SIGNALS Abstract 1 The geometry and properties of discontinuities are very important in the rock mass stability assessment. The GPR method which is able to yield information about the internal structure of resistive rocks was applied in extreme conditions to image sub-vertical cliffs. The profile interpretation allowed to locate several discontinuities whose characterisation required an analysis based on the frequency content of the radar reflection. The possibilities and the limitations of the reflectivity inversion were previously tested with a grid search within the parameter space. In this paper we
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GPR Measurements at the Site of a German Medieval Imperial Palatinate
More LessA029 GPR MEASUREMENTS AT THE SITE OF A GERMAN MEDIEVAL IMPERIAL PALATINATE SUMMARY 1 Measurements with the ground penetrating radar (GPR) are very useful in exploring archaeological sites. The main features are high resolution and fast data acquisition. In practice there are some problems which have to be overcome: low material contrast of the archaeological objects to the surrounding layers and strong reflective layers near the surface. Several processing steps are presented and discussed which were chosen to improve the signal to noise ratio. The results could be tested because parts of the area had been excavated several years ago
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Fast Imaging of a Romano-Celtic Temple with a Decimetric Resolution – 1 Ha in 2 Hours?
More LessA030 FAST IMAGING OF A ROMANO-CELTIC TEMPLE WITH A DECIMETRIC RESOLUTION – 1 HA IN 2 HOURS ? Abstract 1 Archaeological exploration of buried targets with non destructive techniques is becoming more and more important but has to face a specific problem of spatial resolution: most of our heritage is buried in the first meter below the ground surface and in order to obtain a good resolution of images we need a ground resolution of the order of several decimetres. Exploration of areas of more than several hectares with this resolution need lot of time and money and is not
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Rapid and Precise Archaeogeophysical Survey Using a Multi-Sensor Platform (MSP)
Authors I.A. Hill and N. LinfordA031 RAPID AND PRECISE ARCHAEOGEOPHYSICAL SURVEY USING A MULTI-SENSOR PLATFORM (MSP) Abstract 1 I. A. HILL 1 AND N.LINFORD 2 1 Department of Geology University of Leicester Leicester LE1 7RH UK. Email: [email protected] 2 English Heritage Centre for Archaeology Fort Cumberland Fort Cumberland Road Eastney Portsmouth PO4 9LD UK Email: [email protected] Archaeogeophysical surveys are established as vital tools for archaeological investigations. The target physical property contrasts are often small and the anomalies subtle. Magnetic surveys are perhaps the epitome of these surveys where the anomalies sought are only a few nannoteslas in amplitude and of the order of a metre
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MULTISENSOR - A Mobile Geophysical Multi-Sensor System for Archaeological Prospecting
Authors S. Woelz, E. Erkul, W. Rabbel and H. StümpelA032 MULTISENSOR – A MOBILE GEOPHYSICAL MULTI-SENSOR SYSTEM FOR ARCHAEOLOGICAL PROSPECTING Summary 1 We show first results of a new highly mobile multi-sensor system for archaeological prospecting. It has been developed for the geophysical investigation of large kilometer-scale antique settlement areas with high resolution in an economic way. The system comprises a four-wheel drive tractor and a trailer carrying magnetic electro-magnetic and ground penetrating radar sensors. Positioning is performed online using differential GPS. Introduction: New demands for archaeological prospecting E. ERKUL W. RABBEL H. STÜMPEL AND S. WOELZ Institute of Geosciences Geophysics Kiel University Otto-Hahn-Platz 1 24118 Kiel Germany In
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Integrated Inversion of CVES and TEM Data Using Lateral Constraints
Authors A.V. Christiansen, N. Foged, E. Auken and K.I. SørensenA033 INTEGRATED INVERSION OF CVES AND TEM DATA USING LATERAL CONSTRAINTS Summary 1 We present a mutually and laterally constrained inversion between transient electromagnetic (TEM) and geoelectric (DC) data sets. Although both methods measure in some sense the electrical resistivity or conductivity of the subsurface they sample different volumes and have different sensitivities. The different sampling volumes and different sensitivities are exploited by the mutually and laterally constrained inversion algorithm combining the coinciding profile data sets. The output model incorporates the information from both profile data sets to obtain the optimum layered 1D models fitting both data types. All data
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Joint Inversion of TEM and DC Soundings
Authors P.O. Barsukov, E.B. Fainberg and E.O. KhabenskyA034 JOINT INVERSION OF TEM AND DC SOUNDINGS Abstract 1 P.O. BARSUKOV E.B. FAINBERG AND E.O. KHABENSKY Institute of Physics of the Earth RAS Troitsk branch 142190 Troitsk PO Box 30 Moscow region Russia It is well known that DC (direct current) soundings are very sensitive to resistive layers and structures imbedded in section and insensitive to conductive layers. On the contrary TEM (transient electromagnetic method) is sensitive to conductive layers and insensitive to resistive ones. The real paper describes the way of joint inversion both DC and TEM data in 1D class of layered sections providing construction of a
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Interpretation of a Hydrogeophysical Survey – Data from the High-Resolution SkyTEM System
Authors K.I. Sørensen, B. Sørensen, A.V. Christiansen and E. AukenA035 INTERPRETATION OF A HYDROGEOPHYSICAL SURVEY – DATA FROM THE HIGH- RESOLUTION SKYTEM SYSTEM Abstract 1 During the last decade approximately 50 000 ground-based TEM soundings have been carried out in Denmark for groundwater investigations. This number will increase in the future and therefore we have developed a new time-domain electromagnetic (TEM) helicopter system SkyTEM. In the development and design of the SkyTEM system it has been an unchangeable demand that the data quality of the SkyTEM system should be the same or better than the data quality of ground-based systems e.g. the Protem 47 system (40 x 40 m
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Constrained Inversion of Helicopterborne EM Data
By H. ThunehedA036 CONSTRAINED INVERSION OF HELICOPTERBORNE EM DATA Summary 1 Helicopterborne EM data from two surveys in Sweden have been inverted into two-layered models. The surveys were carried out in areas of resistive crystalline rock. The leveling of the data was aided by geophysical measurements on the ground. Ground truth information was also used as constraints during inversion. The data was treated in a regular grid over the survey area and a two-layer model for each grid node was produced. These models were stitched together to give a continuos description of the bedrock resistivity and the soil cover resistivity and thickness
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Empirical Inversion of HEM Data for Sea Ice Thickness Mapping
Authors A. Pfaffling, C. Haas and J.E. ReidA037 EMPIRICAL INVERSION OF HEM DATA FOR SEA ICE THICKNESS MAPPING Summary 1 Since 2001 the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven (AWI) has operated a purpose built unique HEM system to map sea ice thickness in the Arctic and Antarctic. To determine the sea ice thickness from the measured EM field we use an empirical curve fitting approach. The master curve is tuned for every flight leg using measurements over open water between the ice floes in leads or polynyas. The level ice thickness which is a key value for sea ice science and climate
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Magneto-Electric Mapping of 3D Electrical Conductivity Distributions – System Design and Resolution Analysis
Authors A. Verweerd, A. Tillmann, E. Zimmermann, A. Kemna and H. VereeckenA038 MAGNETO-ELECTRIC MAPPING OF 3D ELECTRICAL CONDUCTIVITY DISTRIBUTIONS – SYSTEM DESIGN AND RESOLUTION ANALYSIS Abstract 1 In order to map the electrical conductivity distribution in cylindrical soil columns a combined measurement of the electric potential and the three magnetic field components due to a low frequency current injection is proposed. The magnetic field is measured by means of a vertical moving scanning torus with 24 sensor modules capable of measuring in a range of 200 nT with a resolution of 50 pT without the use of extensive magnetic shielding. Numerical simulations prove the additional value of the magnetic dataset when
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Moisture Dynamics in Urban Soils with High Resolution Geoelectrics
Authors M. Müller, O. Mohnke, J. Schmalholz and U. YaramanciB001 MOISTURE DYNAMICS IN URBAN SOILS WITH HIGH RESOLUTION GEOELECTRICS Introduction 1 Urban soils are subject to strong variations of environmental conditions like in water flow solute transport or heat budget. The research project INTERURBAN has been formed to investigate the dynamics of water and solutes at urban locations with particular attention to the spatial heterogeneity the organic soil substance and soil-biological transformation processes in the unsaturated zone. The objectives of INTERURBAN define also the tasks for geophysics: The development of a noninvasive conception to map water distribution water dynamics and important physical parameters on small scales. Approaches to adopt
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Streaming Potentials Associated with Well-Pumping – Analogical and in Situ Results
By F.A. GassB002 STREAMING POTENTIALS ASSOCIATED WITH WELL-PUMPING – ANALOGICAL AND IN SITU RESULTS Summary 1 Water flowing in a porous media causes natural electrical currents called streaming potentials. Thus during pumping the inflow of water to the well causes a positive potential anomaly above the well. Analogical experiments in a tank during well-pumping show that the piezometric surface acts as a dipolar electrical source. Furthermore measurements of the streaming potentials before during and after pumping show that they are linearly dependent of the variation of the water level thus allowing calculation of the coupling coefficient around the well. This opens some
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