- Home
- Conferences
- Conference Proceedings
- Conferences
Near Surface 2005 - 11th European Meeting of Environmental and Engineering Geophysics
- Conference date: 04 Sep 2005 - 07 Sep 2005
- Location: Palermo, Italy
- Published: 04 September 2005
1 - 50 of 180 results
-
-
Strategies for Time-Lapse Electrical Resistivity Inversion
More LessA005 STRATEGIES FOR TIME-LAPSE ELECTRICAL RESISTIVITY INVERSION Summary 1 Time-lapse electrical measurements are becoming increasingly used to monitor changes induced by man-made or natural dynamic processes. To find the best strategy to invert time-lapse electrical data we tested and compared several inversion strategies found in the geophysical and biomedical literatures i.e. spatiotemporal regularization and difference inversion on synthetic data. Preliminary results show that the spatiotemporal regularization and difference inversion schemes have specific capabilities. The former method allows to better resolve absolute images compared to (spatial) smoothness-constraint inversion and difference inversion whereas the latter technique led to better results when looking
-
-
-
Four Dimensional Inversion of DC Resistivity Monitoring Data
By J.-H. KimA006 Four dimensional inversion of dc resistivity monitoring data Abstract 1 Dc resistivity monitoring has been increasingly used in order to understand the changes of subsurface conditions in terms of conductivity. An approach commonly used is to construct the time-lapse images by independently inverting the measured data acquired at different times. This may result in the time-lapse images contaminated with inversion artifacts. In this paper I propose an algorithm to invert all data sets simultaneously from a long-term monitoring survey. Accordingly we can obtain all the subsurface models at different times by just one inversion process. As a measure of
-
-
-
A New Boundary-Element-Based Singularity Removal Approach for Geoelectric Forward Solver
More LessA007 A new boundary-element-based singularity removal approach for geoelectric forward solver Summary 1 We present a new singularity removal technique for 3D finite-element forward calculations of the geoelectric equations in the presence of significant topography. The technique which is based on the Trefftz boundary-element method (TBEM) allows the singular potential to be calculated numerically and subtracted from the finite-element equations. A numerical experiment demonstrates that the technique is accurate and computationally very efficient. Introduction During the past few decades much effort has been put into the development of numerical solutions of the 3D geoelectrical forward problem. Many solutions found in
-
-
-
Modelling of MRS Signals over 2D Electrically Conductive Structures
Authors M. Braun, I. Rommel, M. Hertrich and U. YaramanciA008 MODELLING OF MRS SIGNALS OVER 2D ELECTRICALLY CONDUCTIVE STRUCTURES Abstract 1 We show for the first time modellings of Magnetic Resonance Sounding (MRS) data influenced by 2D electrical resistivity structures. We demonstrate exemplarily the impact of a 2D electrical resistivity distribution for two typical geological situations: a horizontal block and a dipping layer. We also show the influence of the dipping direction that can be especially seen in the phase values. For studies on 2D water content distributions it is also recommended to consider the associated 2D resistivity distribution. Method Magnetic Resonance Sounding (MRS or Surface Nuclear Magnetic Resonance
-
-
-
A New Regularization for the Inversion of IP Data Based on the Minimum Gradient Support
Authors R. Blaschek, A. Hördt and A. KemnaA009 A new regularization for the inversion of IP data based on the minimum gradient support 1 R. BLASCHEK(1) A. HÖRDT(1) A. KEMNA(2) (1) University of Bonn Institute of Geology Department of Applied Geophysics (2) Agrosphere Institute (ICG-IV) Forschungszentrum Jülich Summary We present a new regularization scheme for the inversion of resistivity and induced polarization (IP) data which supports large resistivity magnitude and phase contrasts. Basis of our approach is the minimum gradient support after Portniaguine and Zhdanov (1999) which tries to minimize the occurrence of parameter contrasts independent of the magnitude of the contrasts. Additionally the spatially varying sensitivity
-
-
-
Geoelectric Surveys to Supplement to Determine the Structure of Hydro-Thermal Systems – Case Study Vulcano
Authors R. Supper, C. Stotter and K. GwinnerA010 GEOELECTRIC SURVEYS TO SUPPLEMENT TO DETERMINE THE STRUCTURE OF HYDRO- THERMAL SYSTEMS – CASE STUDY VULCANO Abstract 1 Geophysical methods provide the tools to investigate 3D volcanic structures and corresponding hhdrothermal systems. Even though seismic and gravimetric data have proven to supply valuable information the application of additional potential field methods is of great benefit for improving this picture. Geoelectric multi-electrode tomographic sections give a detailed image of the subsurface resistivity distribution. The Geological Survey of Austria (GBA) has a huge expertise in this field applied to volcanic areas. From 1996 to 2004 the GBA has conducted dozens of
-
-
-
Two Dimensional Object Orientated Focussing of Geoelectrical Multielectrode Measurements
More LessA011 Two Dimensional Object Orientated Focussing of Geoelectrical Multielectrode Measurements Summary 1 We present a method to reduce automatically the number of geoelectrical multielectrode measurements. The reduction is done by an optimisation of the resulting sensitivity distribution for different measurements compared to an initial sensitivity distribution. The effect of this reduction leads to a gain of time – and consequently the expense will be reduced. The determination of important and unimportant measurements is done by a weighting factor. Measurements with small weights are neglected and vice versa. This procedure called object orientated focussing (OOF) can achieve savings up to 70
-
-
-
Airborne EM – From Anomaly Hunting to 3D Mapping – A Case From Finland
Authors H. Vanhala and I. SuppalaA012 AIRBORNE EM – FROM ANOMALY HUNTING TO 3D MAPPING – A CASE FROM FINLAND Abstract 1 GTK (Geological Survey of Finland) started the Finnish low-altitude airborne geophysical mapping program in 1972. Nearly 90 percent of the land area has been measured so far. During the last ten years airborne EM (AEM) data have turned into a base material in many ground water land use and environmental mapping and monitoring projects. Recent improvements in measurement and interpretation techniques have been giving rise to detailed subsurface conductivity models and expanded the use of AEM data to new applications. This paper discusses
-
-
-
Comparing Time-Domain Reflectometry and Electrical Resistivity Tomography on a Dike Model
Authors J. Rings, C.H. Hauck and H. WörschingA013 COMPARING TIME-DOMAIN REFLECTOMETRY AND ELECTRICAL RESISTIVITY TOMOGRAPHY ON A DIKE MODEL Introduction 1 To ensure the stability of earthen structures like flood protection dikes geophysical measurement methods can be applied. Here the geotechnical engineer is interested in knowing the quantitative water content and how it changes over time. This requires a monitoring system that is able to monitor and predict soil water content over large areas. To this end a combination of two measurement systems is tested. The next project phase will also include numerical simulation as a means of including meteorological factors into the monitoring system. In the
-
-
-
Monitoring of a Groundwater Tracer Using Radiomagnetotellurics (RMT)
More LessA014 MONITORING OF A GROUNDWATER TRACER USING RADIOMAGNETOTELLURICS (RMT) Summary 1 In autumn 2002 a large amount of saltwater was injected into a shallow unconfined aquifer for a period of 7 days. The experiment was accompanied by extensive geophysical monitoring for 10 weeks before during and after the injection. Radiomagnetotelluric field data display a conducting anomaly progressing with the groundwater flow. A comparable anomaly appears in the conductivities determined by groundwater probing. The RMT data have been interpreted using a two-dimensional magnetotelluric inversion code. Inversion results supply detailed information on the heterogeneous geological structure of the aquifer and reveal a
-
-
-
1D LCI-Interpretation Applied to Large Scale SkyTEM Data Sets
Authors N.A. Edsen and L. H. JacobsenA015 1D LCI-interpretation applied to large scale SkyTEM data sets Summary Large-scale airborne TEM data sets have been collected in three areas with very different geological environments. TEM soundings were measured along profiles at a station interval of about 40 meters with the SkyTEM system and interpretation performed with a 1D Laterally Constrained Inversion scheme (1D-LCI). With a careful choice of constraints applied within the 1D-LCI we have been able to dissolve the geophysical models with very good parameter determination and data fitting. A comparison of the results with information from borings shows good agreement between the dissolved geophysical models
-
-
-
Frequency Electromagnetic Modelling to Study Moisture Zones in Salt Mines
Authors G. Kurz, R. Schulz and U. YaramanciA016 Frequency electromagnetic modelling to study moisture zones in salt mines 1 G. KURZ (1) R. SCHULZ (2) and U. YARAMANCI (1) (1) Technical University Berlin Dep. of Applied Geophysics Ackerstr. 71 D-13355 Berlin Germany (2) Leibniz Institute for Applied Geosciences Stilleweg 2 D-30655 Hannover Germany [email protected] Abstract To investigate the stability of mining buildings in salt mines (e.g. galleries pillars caverns chambers) detection and observation of moisture zones is necessary. These zones decreases the natural stability of rock salt and are often responsible for collapsing of parts of the mining building. The electromagnetic method is an useful tool for
-
-
-
Hydrogeophysical Observation of Soil Moisture Variations in the Root Zone
Authors U. Werban and S.A. Al HagreyA017 Z-99 HYDROGEOPHYSICAL OBSERVATION OF Abstract Summary 1 We monitored with hydrogeophysical techniques temporal and spatial variations of soil moisture due to water uptake of roots during two small scale experiments (cm range) and compared single point (e.g. TDR) and two-dimensional (geoelectrical) measurements. Therefore we observed several weeks the distribution of water content with in pots and found (a) regularly diurnal rhythms (b) seasonal variations and (c) significant heterogeneity of soil moisture in space. Introduction SOIL MOISTURE VARIATIONS IN THE ROOT ZONE U. WERBAN AND S. A. AL HAGREY University of Kiel Institute of Geosciences Geophysics Otto-Hahn-Platz 1 24118 Kiel
-
-
-
Time-Lapse Monitoring Using Borehole-to-Surface Electrical Resistivity Tomography
Authors P. Tsourlos, R.D. Ogilvy and P.I. MeldrumA018 Time-lapse Monitoring using Borehole-to- Surface Electrical Resistivity Tomography Abstract 1 Time-lapse Electrical Resistivity Tomography (ERT) has been applied in borehole-to-surface mode to study the leachate generation within an unconfined landfill near Thriplow U.K. Several boreholes were drilled in the landfill to characterize the waste and to establish the concentration and spatial variability of the leachate. To assist this study six of these boreholes were instrumented by installing an electrode array on the outside of the PVC casing prior to completion. Borehole-to surface ERT were collected over two periods (January and April) using mainly Wenner-Schlumberger The data were processed using
-
-
-
Investigation of Broadcast and Low-Induction Number EM to Determine Depth to Saline Soil
Authors A. Smiarowski, J. Macnae and J. ReidA019 Investigation of broadcast and low induction number EM method to determine depth to shallow saline soil Abstract 1 The mapping of the presence and depth to saline waters is of importance in Australian agriculture where historical land clearing has led to a slow and economically troublesome rise in saline water tables. Low induction number EM instruments such as the Geonics EM31 are in common use for mapping the spatial extent of shallow salinity but do not provide reliable depth to salt. A theoretical study has shown that the measurement of E and H fields at carrier wave frequencies from
-
-
-
Mapping Resistivity Variation to Identify Sulphidic Sediments in Sweden
Authors L. Persson, M. Bastani and G. SohleniusA020 Z-99 Mapping resistivity variation to identify sulphidic sediments in Sweden. Introduction 1 Sulphidic postglacial sediments occur below the highest coastline in both Finland and Sweden. The sediments were mainly deposited in the Litorina Sea from about 7000 to 4000 years ago. Acid sulphate soils are formed after oxidation of the iron sulphides (e.g. FeS FeS2) in these sediments. High concentrations of certain trace elements (e.g. Ni Cu and Mn) have been measured in streams which drains areas dominated by acid sulphate soils [9]. These trace elements can cause environmental problems. Figure 1. Location of the Study area in the
-
-
-
High Resolution 2D Inversion of Separated Loop Magnetic Resonance Sounding (MRS) Surveys
Authors M. Hertrich, M. Braun and U. YaramanciA021 High resolution 2D inversion of separated loop Magnetic Resonance Sounding (MRS) surveys Abstract 1 The method of Magnetic Resonance Sounding (MRS) is conventionally used for 1D investigations of the water content distribution with depth. It has proved to provide essential information in hydrogeophysical surveys concerning the total amount of mobile water and thus improving the aquifer localization and characterization significantly. Latest work extend the application of MRS surveys to 2D investigations of the water content distribution. These are the development of MRS measurements with separated loops providing a superior sensitivity to shallow depth and the full 2D inversion of
-
-
-
The Quantitative Capabilities of HEM Inversion for the Sea Ice Case
Authors A. Pfaffling and J.E. ReidA022 The quantitative capabilities of HEM inversion for the sea ice case Summary 1 Semi-empirical methods are routinely used for Helicopter Electromagnetic (HEM) sea ice thickness mapping. Although these methods yield sufficiently accurate thickness data it is of interest to determine whether formal one-dimensional (1D) geophysical inversion could yield improved results. If both the thickness and the ice conductivity could be mapped the results could be used to estimate glaciological parameters such as the age of the sea ice. Sea ice conductivity data could also be potentially used to estimate the strength of the ice sheet which would be valuable
-
-
-
Use of the Linear Grid Array in 2D Resistivity Tomography
Authors G. Fiandaca, R. Martorana and P.L. CosentinoA023 USE OF THE LINEAR GRID ARRAY IN 2D RESISTIVITY TOMOGRAPHY Introduction 1 In resistivity tomography the choice of a particular array rather than another can bring substantial differences in results also depending on the geometry and resistivity of investigated structures. Main differences regard spatial resolution production of artefacts in the images as well as deviation from the true model resistivity. Recently some multi-channel acquisition systems promoted using new array configurations in addition to the “classical” ones that enable many simultaneous measurements for each current injection dipole thus reducing the field-work time significantly. Examples of this kind of arrays are
-
-
-
A Triple-Grid Technique for the 3D Inversion of DC Resistivity Data Incoporating Arbitrary Topography
Authors T. Günther and C. RückerA024 A TRIPLE-GRID TECHNIQUE FOR THE 3D INVERSION OF DC RESISTIVITY DATA INCOPORATING ARBITRARY TOPOGRAPHY Summary 1 We present a novel technique for the determination of resistivity structures associated with arbitrary surface topography. The approach represents a triple-grid dc resistivty inversion technique which is based on unstructured tetrahedral meshes and a finite element forward operator applied to the secondary potential. We use a Gauss-Newton method with inexact line search to fit the data within error bounds. A global regularization scheme using special smoothness constraints is applied. The regularization parameter compromising data misfit and model roughness is determined by an L-curve
-
-
-
Audiomagnetotelluric Sounding (AMTS) at Shallow Depths to Predict Accumulations of Oil-Gas Condensate Raw Stock
Authors E.M. Sheremet, A.V. Antsiferov, V.V. Sukhoi, Y.I. Nikolaev and I.Y. NikolaevA025 Audiomagnetotelluric sounding (AMTS) at shallow depths to predict accumulations of oilgas condensate raw stock Abstract 1 A.V. ANTSIFEROV E.M. SHEREMET V.V. SUKHOI YU.I. NIKOLAEV I.YU. NIKOLAEV Ten-year experience of using AMTS method within the Dnieper-Donets cavity (DDC) of Ukraine to predict and prospect for accumulations of oil-gas condensate raw stock has allowed to create efficient technique of field observations and geoelectric data processing. The employment of AMTS method which resolution throughout the depth is 0.5-2.0 km is based on the observations of the epigenetic transformation of rocks occurring above the oil pool. In the process of epigenetic transformations of
-
-
-
Localization of a Karst Conduit Using Magnetic Resonance Soundings – A Case Study
Authors M. Boucher, K. Chalikakis, J.-M. Baltassat, A. Legchenko and J.-F. GirardA027 Localization of a karst conduit using Magnetic Resonance Soundings a case study Abstract 1 Initially developed for one-dimensional applications Magnetic Resonance Soundings (MRS) technique can be also applied to investigation of two or three dimensional water-filled structures like karst conduits and caves. Numerical modeling reveals that MRS is able to detect water-filled karst. Based on these results field experiments were carried out. The aim of presented experimental study was to validate MRS 2D mathematical model and to develop a methodology of acquisition and interpretation of MRS profile over a karst conduit. It was found that results of 2D inversion
-
-
-
1D and 2D Cole-Cole-Inversions of Time Domain Induced Polarisation Data
More LessA028 1D AND 2D COLE-COLE-INVERSIONS OF TIME DOMAIN INDUCED POLARISATION DATA Summary 1 A new method for the 2D inversion of induced polarization (IP) data in the time domain has been developed. The whole IP transients were observed and inverted into 2D Cole-Cole earth models including resistivity chargeability relaxation time and the frequency constant. First of all a modified time domain electromagnetic algorithm was used to calculate the response of a layered polarizable ground. The transient signals were then inverted using the Marquardt-method to derive the Cole-Cole parameters of each layer. However model calculations showed that the EM effects could
-
-
-
Implementation to Back-Projection Techniques of Resistivity Data
Authors R. Martorana and P.L. CosentinoA029 IMPLEMENTATION TO BACK-PROJECTION TECHNIQUES OF RESISTIVITY DATA Summary 1 In order to obtain well contrasted images by back-projection of resistivity data some modifications to the back-projection algorithm as well as the use of filtering techniques for the sensitivity matrix were proposed (Kotre 1994; Cosentino et al. 1998). To further improve the back-projection algorithm a new implementation is here suggested. Besides a subsequent filtering algorithm of the sensitivity coefficient matrix is proposed. It is aimed to increase resistivity contrasts and to reduce smoothness in tomographic final representation. Finally the proposed technique is tested on synthetic data. Introduction The back-projection resistivity
-
-
-
Non-Linear Resistivity Inversion on 3D Structures with Complex Shapes
Authors L. Marescot, S. Palma Lopes, S. Rigobert, R. Lagabrielle and D. ChapellierA030 NON-LINEAR RESISTIVITY INVERSION ON 3D STRUCTURES WITH COMPLEX SHAPES Summary 1 A non-linear inversion code was presented for the processing of resistivity tomographies on complex 3-D structures using any electrode arrangement. This algorithm uses an original strategy (adjoint-state technique) to minimize the cost function and to avoid high-computation costs. Synthetic modellings have shown that the algorithm can be successfully used to invert resistivity data collected on complex 3-D structures with a large number of data and model parameters. Introduction The finite element method has been used by several authors in the context of direct current electrical resistivity inverse modelling.
-
-
-
Modeling and Monitoring the Tortin Alpine Glacier by Gravity and DGPS Surveys
Authors P. Chassseriau, P. Radogna, P. Logean, V. Lattion and R. OlivierA031 Modeling and monitoring the Tortin alpine glacier by gravity and DGPS surveys 1 Pierrick CHASSERIAU PierVittorio RADOGNA Philippe LOGEAN Vincent LATTION and Raymond OLIVIER Institute of Geophysics. Geosciences & Environment Department. University of Lausanne. Switzerland Abstract Since many years a significant retreat of alpine glaciers is observed. Some of them located in tourist areas have a special interest for ski resorts facilities. That is the case of the 3000 meters high Tortin glacier located on north face of Mont Fort in the Valais state (Switzerland). Several surveys (gravimetry DGPS Georadar) have been carried out in the last years (2001-2005).
-
-
-
Automatic Determination of Dispersion Curves
Authors B. Neducza and L. HermannA032 Automatic determination of dispersion curves Introduction 1 The well known and widely used Spectral Analysis of Surface Waves (SASW) and Multi- Channel Analysis of Surface Waves (MASW) methods of shear wave velocity (Vs) determination have crucial steps. One of these important points is the accurate determination of the dispersion data of Rayleigh waves because obviously these data influence the results of all further processing steps. In the classical SASW the method of determining dispersion data is the cross-power spectrum of surface waves received by two geophones. Although the proper distance of the geophone pair provides good horizontal resolution the
-
-
-
Geostatistical Estimation of Structural Vulnerability
Authors A.V. Christiansen, E. Auken, K. Sørensen, F. Jørgensen and R. JohnsenA033 Geostatistical estimation of structural vulnerability Summary 1 In this abstract we present a newly developed concept using geostatistical estimation and nonlinear inversion to optimize a function translating geophysical resistivity models to geophysical clay thickness. The algorithm uses information on reported clay thicknesses in drill holes. We call it geoStatistical estimation of Structural Vulnerability (SSV). The clay thickness in the upper part of the subsurface is an important factor for the water infiltration speed and thereby the vulnerability of underlying aquifers to pesticides nitrate etc. Drill hole information contains the most detailed information on clay thicknesses but most often drill
-
-
-
Characterization of Fractured Rock Aquifers by Surface Geophysical Methods
Authors A. Legchenko, M. Descloitres, L. Ruiz, M. Reddy, J.-F. Girard and M. SekharA034 Z-99 Characterization of fractured rock aquifers by surface geophysical methods Summary Comparison of MRS results with static water level measurements and hydraulic conductivity estimation in boreholes shows that MRS method could be an efficient tool for investigation of weathered part of crystalline aquifers with the effective porosity greater than 1%. It was shown using both numerical modeling and field measurements that the MRS method allows characterizing two- dimensional subsurface formations. Presented field example proves that a combination of the MRS with 2D electrical imaging tool improves geophysical results in complex heterogeneous gneissic formations of Southern India. Introduction Magnetic Resonance
-
-
-
Monitoring Water Content in the Porous Medium with 4-D GPR – Physical Model Experiment
Authors C. Kim and J.J. DanielsA035 Monitoring Water Content in the Porous Medium with 4-D GPR: Physical Model Experiment Abstract 1 A physical model experiment using a sand and gravel-filled tank was conducted to investigate the response of Ground Penetrating Radar (GPR) over simulated hydrogeologic conditions. Repeated GPR measurements were made on a 3-D survey grid on the surface of the tank at each level of water table for an extended period of time during raising and lowering the water table in stages to monitor changes in the sand and gravel layers in the tank. The results of the experiment during fluctuating water table demonstrate
-
-
-
Numerical Modelling of Ground Penetrating Radar Antennas
More LessA036 NUMERICAL MODELLING OF GROUND PENETRATING RADAR ANTENNAS Introduction 1 Numerical modelling of ground penetrating radar (GPR) can significantly enhance our understanding of the GPR’s detection mechanism especially in complex environments. In addition models could aid GPR data interpretation. There are a number of numerical methods that can be used to develop a forward GPR model. One of the most versatile and powerful technique is the Finite-Difference Time-Domain (FDTD) method pioneered by Kane Yee (1966). FDTD has been used successfully to model GPR responses from simple targets assuming either a two dimensional or a three dimensional geometries (Holliger et. al.
-
-
-
Use of Acoustic Method to Study Rock Mass in Tunnel Engineering
Authors A. Antsiferov, M. Tirkel, A. Glukhov and V. AntsiferovA037 Use of acoustic method to study rock mass in tunnel engineering 1 A. ANTSIFEROV M. TIRKEL A. GLUKHOV V. ANTSIFEROV UkrNIMI NANU 291 Chelyuskintsev St. 83121 Donetsk Ukraine Abstract In this article procedure for acoustic prediction of structural-tectonic structure of rock mass is given through a case history of engineering survey in construction of the tunnel through the Markotkhsky ridge (Krasnodarsky krai Russia). Introduction Many underground structures require engineering-geological research at all stages of design and construction. Conducting of research is of special significance in tunnel engineering. Tunnels are both difficult for construction and maintenance and also expensive and
-
-
-
Advances in Surface Wave Methods – Cascaded MASW-SASW
Authors R.S. Westerhoff, J.H. Brouwer and J.A.C. MeekesA038 Advances in surface wave methods: cascaded MASW-SASW Abstract 1 The application of the MASW method in areas that show strong lateral variations in subsurface properties is limited. Traditional SASW may yield a better lateral resolution but the dispersion curves (and thus the subsurface models) obtained with the method may be poor. The joint application of MASW and SASW is proposed to allow for a robust determination of dispersion curves and the incorporation of lateral changes in subsurface properties. The method involves the application of MASW for the initial estimation of a gross dispersion curve. From the gross dispersion curve
-
-
-
Time-Lapse Shear-Wave Seismic to Define the Lateral Extent of Impact Due to Sheet Piling
By R. GhoseA039 Z-99 Time-lapse shear-wave seismic to define the lateral extent of impact due to sheet piling Summary 1 It has not been possible so far to measure in the field in a laterally continuous manner the impact of sheet piling on subsoil structures and hence potentially on adjacent buildings. We propose the idea of time-lapse shear-wave seismic reflection surveys for this purpose. Result on field data shows that despite the usual difficulty to achieve sufficient reproducibility in seismic field data acquisition the impact of sheet piling on the soil boundaries can still be distinctly recognized in the time-lapse shearwave data.
-
-
-
Seismic Reconnaissance beyond the Faces of an Advancing Coal Mine Roadway
Authors K. Essen, R. Misiek and W. FriederichA040 SEISMIC RECONNAISSANCE BEYOND THE FACES OF AN ADVANCING COAL MINE ROADWAY K. ESSEN 1 R. MISIEK 1 AND W. FRIEDERICH 2 Summary 1 Within the scope of the current project the aim is to develop a non-destructive investigation technique using seismic waves to obtain information on the state of the rock ahead of the faces of a coal mine roadway. First test measurements were carried out in a mine of the Deutsche Steinkohle AG (DSK) in the northern Ruhr area. A series of disturbances are expected beyond the faces of this roadway from geologic investigations. Synthetic seismograms were calculated
-
-
-
Use of Surface Waves for Geotechnical Characterization of Neogene Deposits–The Glyfada, Athens Case Study
Authors K. Symeonidis, T.D. Papadopoulos and J. AlexopoulosA041 Z-99 Use of surface waves for geotechnical characterization of 1 neogene deposits – The Glyfada Athens case study. AUTHORS K. Symeonidis T.D. Papadopoulos and J. Alexopoulos University of Athens Geophysics-Geothermics Dpt. Panepistimiopolis Zographou 15784 Athens Greece Abstract Summary. The surface waves method was used in this case study as an alternative and efficient tool for geological and geotechnical investigation. The site is located at Glyfada Athens where neogene formations mainly composed by clayish layers with intercalations of conglomerates are present. The results were compared with data from geotechnical investigation and seismic refraction data. Introduction. The test site is located
-
-
-
Assessment of the Quality of Radar Results on Bridge Decks
More LessA042 Z-99 Assessment of the quality of radar results on Abstract Summary 1 bridge decks JOHANNES HUGENSCHMIDT EMPA Ueberlandstrasse 129 8600 Dübendorf Switzerland [email protected] Ground-Penetrating-Radar has become an important tool for non-destructive testing of concrete bridges. The evalution of the quality of radar results is in most cases restricted to very few points on real objects or to laboratory experiments. In recent years Empa had the opportunity to complete several projects aiming at the evaluation of radar results on concrete bridges. This paper presents an overview of the results giving a quantitative estimate of the quality of radar results. Introduction
-
-
-
Assets and Drawbacks of Draped Airborne-Magnetic Surveys in Highly Magnetized Regions – A Case Study
Authors C. Stotter and R. SupperA043 ASSETS AND DRAWBACKS OF DRAPED AIRBORNE-MAGNETIC SURVEYS IN HIGHLY MAGNETIZED REGIONS – A CASE STUDY Summary 1 High resolution draped airborne magnetic surveys are ideal for the collection of huge amounts of data in a relatively short time especially in areas that are not directly accessible from the ground like young volcanic morphologies. Technological developments have steadily increased the precision and consequently the possibilities of the airborne magnetic method. This however demands a corresponding increase of the accuracy of processing and of positioning especially in highly magnetized areas. Furthermore some of the basic assumptions of potential field methods (in
-
-
-
Airborne Geophysical Surveys Applied to Urban/Brownfield Investigations
Authors D. Beamish, R.J. Cuss and E. TartarasA044 Z-99 AIRBORNE GEOPHYSICAL SURVEYS APPLIED TO URBAN/BROWNFIELD INVESTIGATIONS 1 Abstract A number of airborne geophysical surveys have now been conducted in the UK using a fixedwing system operated jointly by the British and Finnish Geological Surveys. The system provides magnetic radiometric and frequency domain electromagnetic survey measurements. Regulatory survey permissions force a variety of flight elevations typically between 54 to 244 m. On the fringes of major conurbations we encounter urban greenspace and brownfield areas. These areas may contain mixtures of infrastructure and built structures together with derelict and green areas. In order to provide valid interpretations of the
-
-
-
Geophysics Applied in Tunnel Pilot Boreholes for Pre-Grouting Design Parameters
Authors E. Heikkinen, M. Lahti, E. Tammisto, H. Ahokas and T. AhokasA045 GEOPHYSICS APPLIED IN TUNNEL PILOT BOREHOLES FOR PRE-GROUTING DESIGN PARAMETERS Abstract 1 Geophysical logging was used in two pilot boreholes of an access tunnel to underground nuclear waste storage to provide design information for pre-grouting and support. Boreholes were diamond drilled from ground surface and tunnel. The surveys in first borehole were used to design the works and the advised methods were applied in the second pilot borehole drilled during tunnel excavation within a period of three days after which the excavation continued immediately and was interrupted over minimal time period. Logging methods were optical imaging flow logging borehole
-
-
-
Resistivity Imaging for Mapping of Quick Clays for Landslide Risk Assessment
Authors T. Dahlin, V. Leroux, R. Larsson and K. RankkaA046 Z-99 Resistivity Imaging for Mapping of Quick Clays for Landslide Risk Assessment Introduction 1 T. DAHLIN 1 V. LEROUX 1 R. LARSSON 2 and K. RANKKA 2 1 Engineering Geology Lund University Box 118 S-221 00 Lund Sweden Quick clay in Sweden is defined as clay with a sensitivity of 50 or more and fully remoulded shear strength of less than 0.4 kPa (Karlsson and Hansbo 1989). The sensitivity is the relation between the undisturbed and the fully remoulded undrained shear strength. The only reliable method for the detection of quick clay used so far in Sweden has been
-
-
-
Gravity Mapping and Modelling of Buried Quaternary Valleys in Southern Jutland (Denmark)
Authors U. Casten, S. Thomsen, K. Snopek and C. GramA047 Gravity Mapping and Modelling of Buried Quaternary Valleys in Southern Jutland (Denmark) Abstract 1 Buried valeys in Denmark are utilised for water supply and are the object of intensive investigations to ensure future water resources. Geophysical techniques are applied to localise and outline the structure of the valleys. Gravity surveying is suitable to detect small and in many cases positive anomalies of the valleys within the Earth’s gravity field. In the case of the Bredebro valley situated in southern Denmark mapping has successfully been used to outline the lateral extent of the valley while inversion of the residuals gave
-
-
-
Surface Wave Methods to Explore Shallow Active Faults
Authors F. Nguyen, S. Garambois and D. JongmansA048 Surface wave methods to explore shallow active faults F. NGUYEN 1 S. GARAMBOIS 2 AND D. JONGMANS 2 Summary 1 In active fault survey surface waves are often discarded when using seismic refraction tomography and reflection methods. However surface waves offer many advantages (e.g. high signal to noise ratio and moderate sensitivity on the presence of water) and are being increasingly used. In this paper we propose to use signal processing tools the stacked spectra method and a Green function mapping technique to detect and characterize a step structure using synthetic and field data. The results show that the
-
-
-
The CAMI Project – Example of High-Resolution Seismic Survey to Study Shallow Aquifer
Authors M. Giustiniani, F. Accaino, A. Affatsto, E. del Negro and D. Nieto YabarA049 The CAMI project: Example of high-resolution seismic survey to study shallow aquifer Abstract 1 M. GIUSTINIANI 1 F. ACCAINO 1 A. AFFATATO 1 E. DEL NEGRO 1 and D. NIETO YABAR 1 1 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale Borgo Grotta Gigante 42C 34100 Trieste Italy In this paper we present the project entitled “Water-bearing characterization with integrated methods (CAMI)” supported by European community (LIFE). The project gives a contribution to the realization of the 2000/60/CE using a integrated method to characterize the hydrographical district and to analyse the environmental impact of the human activities and their
-
-
-
Estimation of Quality Factor from Seismic Refraction Data
Authors L.V. Socco, S. Foti and D. BoieroA050 Estimation of Quality Factor from seismic refraction data Summary 1 Several techniques for estimating the quality factor Q from refraction data have been implemented and tested on experimental data. The results show a reasonable agreement among the different estimates although the obtained values are quite small. Frequency domain techniques allow for the recognition of inherent dependence of Q from frequency in agreement with recent laboratory results and lead to estimates closer to values inferred by in situ and laboratory tests for the same geological formation in a site nearby. Introduction The estimation of dissipative properties of near surface sediments
-
-
-
Shallow Surface-Wave Dispersion Applied to the Study of Landslides – An Example in the Jura Mountains, Western Switzerland
Authors J. Demand and F. MarillierA051 SHALLOW SURFACE-WAVE DISPERSION APPLIED TO THE STUDY OF LANDSLIDES: AN EXAMPLE IN THE JURA MOUNTAINS WESTERN SWITZERLAND. Introduction 1 In Switzerland landslides represent a major geologic hazard. Each year landslides cause damages that affect civil engineering structures and have important financial consequences. Thorough understanding of failure type sliding mechanism and cause of landslides is required to effectively mitigate their impact. Typically studies of landslides and slope instabilities make use of geotechnical hydrological and GIS monitoring techniques. Geophysical surveys can help better understand landslides by providing information about their internal structure and seismic refraction profiling and electrical resistivity surveys have
-
-
-
High Resolution Geophysical Measurements for the Investigation of Salt Structures in Depth of 250 m
Authors D. Orlowsky and B. LehmannA052 High Resolution Geophysical Measurements for the Investigation of Salt Structures in Depths of 250 m Abstract 1 To explore salt structures high-resolution geophysical techniques have been developed and applied during the past decade. The applied methods are gravity resistivity magnetics and especially electromagnetic methods as for example georadar which deploys the propagation of electromagnetic waves. Nevertheless for all these methods it is necessary to bring the instruments as close as possible to the object of investigation i.e. salt. This is performed with the help of boreholes or roadways in the salt layer. For the detection of clefts and caverns
-
-
-
S/N Enhancement by Radon Transformation in Ultra Shallow SH-Wave Reflection Investigations
Authors T.D. Papadopoulos, P. Kambouris and J. AlexopoulosA053 S/N enhancement by radon transformation in ultra shallow SH-wave reflection investigations P. Kambouris T.D. Papadopoulos and J. Alexopoulos University of Athens Geophysics-Geothermics Dpt. Panepistimiopolis Zographou 15784 Athens Greece 1 Abstract Summary. A short shear (SH) wave profile was collected as a part of a wider experiment involving P- and S-wave reflection and refraction measurements for further processing. The purpose of the experiment was to examine the efficiency of ultra shallow bedrock surface by SH reflection imaging commonly implemented in engineering applications. The original SH data suffer from direct refracted guided and surface waves interference. In some Common Shot Gathers
-
-
-
Outlook on the Possibility for Slope Stability Evaluation According to Petrophysical Data
By A. FrasheriB005 OUTLOOK ON THE POSSIBILITY FOR SLOPE STABILITYEVALUATION ACCORDING TO PETROPHYSICAL DATA Abstract 1 Results of the geophysical data for in-situ evaluation of the physical-mechanical properties of the rocks in the unstable slopes in Albania are presented. Albania represents a mountainous country with complicated geology. There are unstable mountain and hill slopes. Developing of new landslides or re-activation of the old ones is mainly due to construction works. Special constructions such as hydrotechnical works civil industrial urban and rural constructions and constructions in the infrastructure particularly during last years as well as destroyed equilibrium in ecological systems through deforestation etc.
-
-
-
Geophysical and Seismic Noise Investigations of a Clayey Earthflow
Authors O. Meric, S. Garambois, D. Jongmans, G. Grandjean and J.-P. MaletB006 Geophysical and seismic noise investigations of a clayey earthflow Summary 1 The Super-Sauze earthflow (South Alps Fig. 1) is a clayey flow-like landslide characterized by a complex vertical structure associating a slip surface and a viscoplastic plug. In order to evaluate the probability of the earthflow to mobilize into a debris flow it appears of primary interest to image and characterize its internal structure. These purposes are difficult to achieve due to the rough topography of the site and to contrasted variations of the mechanical hydrological and geometrical characteristics. The aim of this study is to evaluate the potential
-