The Vence landslide is a rotational landslide around fifteen meters deep, regulated by the site hydrology characterized by the coexistence of two groundwaters, and constrained between two major faults.
The landslide occurs at the interface of a combination of very permeable sand and clay containing unconfined groundwater, and fractured and faulted limestone, less permeable but allowing fluid tranfers deep down.
The landslide is mainly governed by the circulation of fluids through sands and the groundwater flow between deep and perched watertables, by the path of faults, creating the destabilization of the slope by shifting its stability criteria.
It is interesting to note that the clay sands composing the slide show high facies variations inside their mass. These variations take a main part into the fluid circulations inside the slope and into the sliding movements.
Longitudinal cross section of the slope showing the lateral facies variations in clay sands