In-situ geophysical and hydro-geochemical monitoring to infer landslide dynamics (Pégairolles-de-l'Escalette landslide, France)

The Pégairolles-de-l'Escalette landslide is located in the central part of the Languedoc Region (Southern France). It corresponds to a deep-seated landslide (>50 m of thickness) with extremely slow slip displacement (3–4 mm/year). In this area, the current landslide activity is associated with intense precipitation events (300–500 mm in a few days) and the related dissolution of Triassic evaporite layers at depth. Considering a relatively simple geological context and a landslide mainly controlled by slope hydrogeology, this site constitutes a natural observatory to study the impact of large rain events on slope kinematics.