The slope movements within the Mondores graben (Drome, France); the interaction between geology, hydrology and typology

摘要

The Mondores graben in the south-eastern French Alps is an uncommon structural feature,which originates in a complex polyphonic tectonicevolution. In contrast with its immediate surroundings,with hardly any huge landslides, the Mondores grabenis characterised by various types of landslides. A hugesagging caused part of the limestone cliff to subsidesome 50 m within 50 years. Two recent mud flows thatoccurred were considered a potential threat to someinhabited places downstream. The hydrologic aspectsof the Boule-Mondores landslide resemble the geology:infiltration (and karst input?) in the rock-slidingzone and exfiltration in the marls resulting in slumpsand mud flows. The mass movement interactions couldbe explained by a structural geology analysis withgeodetic monitoring using different techniques. It isalso shown that hydrochemistry as well as geophysicalsurveys are of importance in unravelling the hydrologicsystems and the geological subsurface structures. Thepresent paper aims at explaining the geological controlof the different slides in view of estimating theirpotential danger. Understanding the geologicalstructure and its evolution therefore is a necessary prerequisite.