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In-Situ Geophysical and Hydro-Geochemical Monitoring for Landslide Dynamics (Lodève Landslide, France)
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 24th European Meeting of Environmental and Engineering Geophysics, Sep 2018, Volume 2018, p.1 - 5
Abstract
The Lodève landslide is located 60 km northeast of Montpellier (South of France). It corresponds to a deep-seated landslide (up to 50 m depth) with a slow slip displacement (4–6 mm/year). In this area the landslide activity is associated with intense precipitations events (called “Cévenol events”, 300–500 mm in few days) and the related dissolution of Triassic evaporite layers at depth. Considering a relatively simple geological context and the presence of a unique triggering factor, this landslide corresponds to a preferential natural observatory to study the impact of large rain events on the slow slope kinematics. A downhole monitoring was conducted since 2012 in order to image the water flows within the landslide in order to better understand the role of fluids in the slope instability. The landslide is investigated down to 60 m depth by two in situ permanent observatories for a geophysical (electrical resistivity and deformation) and an hydrogeochemical monitoring (pressure, pH, temperature, electrical conductivity, fluid sampling). This instrumentation helps to identify and characterize the active slip zones in the underground. The first results point out the relevance of the downhole monitoring to progress towards a better understanding of internal landslide processes in relation to climate forcing.