Some considerations on the mechanics of a large earthslide in stiff clays

This paper reports some considerations about mechanisms of movement of a large slow earthslide in Southern Italy. The main features of the displacement field are: uniformity in each transversal section, decrease in the downslope direction and only slight seasonal rate variations. Among the possible causes of movements, erosion induced by stream waters at the foot of the landslide seems the most probable one. Movements localized at the foot are clearly shown by geomorphological signs and fully justified by a simple back analysis based on limit equilibrium methods. The influence on the global safety factor by local instability of the foot is analysed by means of a simplified 2D numerical simulation.