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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
41 - 60 of 180 results
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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
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Multi-Method Geophysical Survey for the Study of a Holocene Landslide System
By O.N. CutlacB007 Multi-method geophysical survey for the study of a Holocene landslide system Introduction 1 Landslides are complex structures and their study requires the use of complementary techniques such as GPR electrical resistivity or seismic refraction. Ancient landslide systems are particularly difficult to characterize as they normally display post-landslide sedimentation and compaction of debris. In general pre-landslide stratification is not preserved and the slump deposits will appear as areas showing chaotic features diffractions (in a GPR profile) as areas bounded by irregular interfaces (in a seismic refraction model). Refraction seismic-electrical resistivity measurements represent the most common combination of geophysical methods for
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Geophysical Studies in Two Landslide Sites in Turkey
Authors M.G. Drahor, G. Gokturkler, M.A. Berge and T.O. KurtulmusB008 GEOPHYSICAL STUDIES IN TWO LANDSLIDE SUMMARY SITES IN TURKEY 1 In this study two landslide sites (Kadifekale-İzmir and Zeytinli Tepe-Söke Turkey) were investigated by resistivity self-potential seismic refraction and electromagnetic-VLF methods. Resistivity data were collected with multi-electrode measuring system and then processed by 2-D inversion technique. Also the seismic data from Kadifekale landslide area were processed by using the refraction tomography method. After all processing the geometry and boundary of the landslides the characterizations of slipped mass and the thickness of disturbed and undisturbed zones were clearly determined. Keywords: Electromagnetic-VLF landslide resistivity inversion seismic tomography selfpotential Turkey INTRODUCTION M.
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Geophysical Data Fusion by Fuzzy Logic for Imaging Earthflow Mechanical Behavior
Authors G. Grandjean, J.P. Malet, A. Bitri and O. MericB009 Z-99 Geophysical data fusion by fuzzy logic for imaging earthflow mechanical behavior Introduction 1 G.GRANDJEAN 1 J.P. MALET 2 A.BITRI 1 O.MERIC 3 1 BRGM BP 6009 Orléans France 2 Faculty of Geosciences UCEL University of Utrecht P.O. Box 80.115 3508 TC Utrecht Netherlands 3 LIRIGM University Joseph Fourier Maison des Géosciences F-38041 Grenoble Cedex 9 France The aim of this work is to combine the geophysical parameters P-wave velocity (Vp) S-wave velocity (Vs) and electrical resistivity (ρ) for describing the structure of landslides in term of mechanical behavior. The study is focused on the Super-Sauze site (Fig.1; Alpes-de-Haute-Provence
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The Contribution of Electrical Resistivity Measurements to the Analysis of Landslide Events
Authors E. Piegari, R. Di Maio, G. Giordano, P. Capizzi, R. Curciotti, L. Milano and M. NicodemiB010 THE CONTRIBUTION OF ELECTRICAL RESISTIVITY MEASUREMENTS TO THE ANALYSIS OF LANDSLIDE EVENTS Abstract 1 In order to gain insight into the study of natural avalanches dynamics we illustrate a statistical model based on a dissipative dynamical variable associated to a position dependent factor of safety field. This model as experimentally demonstrated is able to reproduce the complex structure of landslide events such as power-law distributions. In this paper we introduce an explicit dependence of the safety factor on the electrical resistivity to simulate landslide events in pyroclastic soils. An application of the model to data acquired in a test
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A Complex Geoscientiffic Strategy for Landslide Hazard Mitigation – Case Study Sibratsgfäll
More LessB011 A COMPLEX GEOSCIENTIFIC STRATEGY FOR LANDSLIDE HAZARD MITIGATION – CASE STUDY SIBRATSGFÄLL Abstract 1 A short period of heavy precipitation and the rapid melting of snow in spring of 1999 initiated a catastrophic landslide on the South-flank of the Rubach Valley near Sibratsgfäll in the federal state of Vorarlberg (Austria). The 1.4 km 2 wide slide area covered from 830 m to 1500 m seelevel. The movement rates of rock- and debris bodies involved exceeded up to 1m per day. A complex geoscientiffic research programmwas initiated shortly after the first slide activity was noticed. The study incorporated a geo-morphological
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A Complex Airborne Geophysical Strategy for Volcanic Risk Mitigation at the Aeolian Island
Authors R. Supper, C. Stotter, K. Motschka, I. Schattauer, B. Meurers, S. Okuma and M. ChiappiniB012 A COMPLEX AIRBORNE GEOPHYSICAL STRATEGY FOR VOLCANIC RISK MITIGATION AT THE AEOLIAN ISLANDS Abstract 1 During recent years a complex airborne geophysical program has been stated at the Eolian Islands Sicily to investigate the airborne geophysical methods for their application to volcanic risk mitigation. The main focus was concentrated on the airborne magnetic method especially repeated magnetic measurements. So far the areas of Vulcano-Lipari Salina Panarea and Stromboli have been surveyed using high resolution airborne magnetic mapping. Within this presentation the achieved advances and encountered problems will be discussed. Further on the results of measurements and their applicability using
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Geophysical Data in the Reconstruction and Characterization of Plio-Quaternary Sediments
Authors L. Orlando, G. Pelliccioni and P. MarsanB013 GEOPHYSICAL DATA IN THE RECONSTRUCTION AND CHARACTERIZATION OF PLIO-QUATERNARY SEDIMENTS Abstract 1 This paper presents a case study on the capability of geophysical methods to reconstruct and characterize the surficial formations of a complex geological area. The area is located in a high seismic risk zone where there is contact between the Laziale-Abbruzzese and Umbro- Marchigiana seriers (central Italy) and where Plio-Quaternary sediments fill the tectonic valleys. The geophysical surveys collected on the outcropping Plio-Quaternary sediments include refraction P- and SV-waves high-resolution seismic reflection vertical electrical soundings (VES) and electrical tomography. The geophysical data were constrained with drillings and
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Shear Wave Velocity-Depth Determination for the Upper Rhine Mid/South Seismic Risk Microzonation
Authors U. Polom, D. Fäh, H.-B. Havenith, C. Pohl, A. Roullé, S. Stange and B. SteinerB014 SHEAR WAVE VELOCITY-DEPTH DETERMINATION FOR THE UPPER RHINE MID/SOUTH SEISMIC RISK MICROZONATION Summary 1 During the spatial extension of the existing seismic microzonation studies of the city of Basel (Fäh et al. 1997) to the adjacent urban areas of Weil a.R. Lörrach in Germany and St. Louis Huningue Village-Neuf in France the spectral analysis of Rayleigh waves and combined shear wave seismic refraction reflection and VSP measurements should support the subsurface velocity-depth structure estimation by H/V-measurements. Due to the different alluvial sedimentation cycles the adjacent Rheingraben fault zone and a long period of anthropogenic activities inhomogeneous shear wave velocity
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Borehole Characterisation of Saturated Unconsolidated Sediments
More LessB015 Borehole characterisation of saturated unconsolidated sediments Summary 1 Seismic velocity and density of clastic sedimentary rocks usually increases with depth due to compaction and porosity reduction. In fully saturated environments Vp velocity trend is manly affected by water velocity and sediments compaction Vs velocity depends on quality of surface contact between matrix grain. Seismic measurements on 40 meters depth borehole were conducted according two different schemes: downhole with a single shots close to the borehole using a string four 3-component geophones (four geophones) and a walkaway VSP using a string of hydrophones. The main objective of the experiments was
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Well Logging and Seismic Attributes for the Best Velocity Model of Rock Formation
Authors K. Wawrzyniak, J. Jarzyna and A. BugajskiB016 Well logging and seismic attributes for the best velocity model of rock formation Abstract 1 A comparison of log measurements and results of the comprehensive interpretation in aspect of mineral composition porosity and saturation determination in borehole profile with seismic attributes was performed in the Miocene sandy-shaly formation in the Polish part of the Carpathian foredeep. A detailed analysis of slowness in several boreholes showed once more that construction of velocity model only on the basis of sonic logs in the sedimentary succession consisted of thin sandstone mudstone and siltstone laminas saturated with gas is very difficult and in
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