Geophysical investigation of landslides : a review

Abstract

Abstract. -In the last two decades, shallow geophysics has considerably evolved with the emergence of 2D spatial imaging, then 3D spatial imaging and now 4D time and space imaging. These techniques allow the study of the spatial and temporal variations of geological structures. This paper aims at presenting a current state-of-the-art on the application of surface geophysical methods to landslide characterization and focuses on recent papers (after 1990) published in peer-reviewed International Journals. Until recently, geophysical techniques have been relatively little used for the reconnaissance of landslides for at least two main reasons. The first one is that geophysical methods provide images in terms of physical parameters which are not directly linked to the geological and mechanical properties required by geologists and engineers. The second reason shown through this study probably comes from a tendency among a part of the geophysicists to overestimate the quality and reliability of the results. This paper gave the opportunity to review recent applications of the main geophysical techniques to landslide characterisation, showing both their interest and their limits. We also emphasized the geophysical image characteristics (resolution, penetration depth) which have to be provided for assessing their reliability, as well as the absolute requirements to combine geophysical methods and to calibrate them with existing geological and geotechnical data. We hope that this paper will contribute to fill the gaps between communities and to strength of using appropriate geophysical methods for landslide investigation. Reconnaissance géophysique des glissements de terrain : Etat de l'artMots clés. -Glissements de terrain, Investigations géophysiques, Etat de l'art Résumé. -Depuis 20 ans, la prospection géophysique à faible profondeur a considérablement évolué avec l'apparition de techniques d'imagerie 2D (x,z), puis 3D (x,y,z) et maintenant 4D (x,y,z,t), qui permettent de considérer les variations spatiales et temporelles des objets géologiques étudiés. A partir de la littérature internationale, nous tentons de faire une synthèse sur l'application des méthodes géophysiques à l'étude et au suivi des mouvements de terrain qui sont des structures complexes et évolutives. Paradoxalement, il apparaît que l'utilisation des techniques géophysiques pour la reconnaissance des mouvements de terrain est restée jusque récemment relativement limitée pour deux raisons principales. La première vient de la réticence d'une partie des ingénieurs et des géologues d'appliquer des techniques complexes qui ne fournissent pas des données géologiques, hydrogéologiques ou mécaniques directement utilisables. La seconde raison, apparue lors de cette étude, résulte de la tendance d'une partie de la communauté géophysique de surestimer la qualité et la fiabilité des résultats obtenus. A travers cette synthèse des publications, nous passons en revue les applications récentes des principales méthodes géophysiques aux mouvements de terrain en illust...

Estimating soil suction from electrical resistivity

“…Jongmans and Garambois, 2007). The resistivity tomographic approach, in fact, provides a very detailed image of subsurface resistivity distribution on the basis of rock and soil resistivity contrasts.…”

“…In recent years, the application of geophysical methods to landslide characterization and monitoring has greatly increased (Jongmans and Garambois, 2007;Wilkinson et al, 2010). The main advantage of geophysical methods is that they are non-invasive techniques, enabling the variations of some physical quantities in large buried volumes to be measured; this is in contrast to remote sensing or aerial photography, which can only provide surface information, or to borehole and penetration tests, which only provide subsurface data in small volumes around porous probes.…”

Fracture System Mapping Using Pressure Probe Method

“…For this aim geophysical techniques -which are summarized e.g. by Jongmans and Garambois (2007) -may be very useful. The goal of the applied geophysical techniques used to be the horizontal and/or vertical delineation of the sliding volume or -more rarelythe study of the inner structure of the landslide or the characterization of the eventually existing sliding surface.…”

Combining Seismic Noise Techniques for Landslide Characterization

“…There are a significant number of methods, which mainly include remote-sensing and aerial techniques, geological and geomorphological mapping as well as geophysical and geotechnical techniques, which have been adapted to characterize landslides (see the pioneering work of Bogoslovsky and Ogilvy (1977) as well as the reviews by Fell et al (2000) and Jongmans and Garambois (2007)). In particular, the recent emergence of 2D and 3D geophysical imaging techniques has dramatically increased their attractiveness for landslide applications, having the major advantage of giving continuous information about the studied body.…”