Geophysical and geotechnical characterization of a slow moving landslide in the Trièves area (Champ du Mouton landslide, Isère)

M2 internship (pro), 5 to 6 months, academic year 2019-2020

Landslides are widespread in mountainous regions and pose major environmental problems, particularly in land use planning. Among these phenomena, clay slides are a very complex type of landslide because they can undergo unpredictable and sudden acceleration phases and evolve into flows. In order to investigate the geometry and triggering mechanisms of landslides, geophysical imaging methods, coupled with conventional geotechnical surveys, are now widely used and allow for better characterization of these objects.

The overall objective of the internship is to study one of these ground movements located in the Trièves area (South Isère). The Champ du Mouton landslide (CDM) is located south of the village of Sinard. It borders the landslide of the Combe d’Harmalière, which was the site of a brutal reactivation in June 2016. More precisely, the objective of the internship is to characterize the geology and geotechnical conditions (lithology, hydrogeology, shear surfaces) in the inhabited area of the CDM slide. A preliminary synthesis of existing data will be conducted (surface movements, inclinometric surveys, geotechnical surveys, etc.). The lithology will be determined using geophysical surveys (electrical resistivity, seismic velocities). These techniques will also highlight the groundwater table as well as the most superficial failure surfaces down to about 20 m. In addition, ambient seismic noise should be used to determine the depth of carbonate bedrock and to estimate the total thickness of quaternary clays. The interpretation of these data will be conducted in conjunction with a field analysis (crack mapping, moutonnements, wetlands, etc.) and a geomorphological analysis of remote sensing data.
The intern may also be required to participate in research activities currently being conducted at the Harmalière site, a landslide adjacent to the CDM.

Prerequisite
Subsurface geophysical prospecting (electrical methods etc.) : acquisition, processing and inversion. Knowledge of geology will be appreciated.

Development
The internship will take place at the ISTerre in Grenoble. Several trips and field work phases (daily outings) are to be planned throughout the internship.

Conditions
Conventional internship allowances.
Based at the ISTerre in Grenoble.

Candidature
CV and cover letter to be sent by email to Grégory Bièvre.