The BasentoValley: a natural laboratory to understand the mechanics of earthflows

Earthflows in tectonized clay shales are widespread in the Apennine Chain ofSouthern Italy. This paper aims to outline their most significant features, on the basis of the results of a study carried out in the high Valley of the Basento river. In particular, the results of displacement and pore pressure monitoring allowto outline a general framework of the earthflow mechanisms, highlighting the strong relationshipbetween morphological aspects, kinematic behaviour and slope stability conditions, and showing the important role of pore pressures. It is shown that after triggering, the soil mass is so softened to behave as a viscous medium: the movement of the landslide body has the features of a flow from moderate to rapid [CRUDEN and VARNES, 1996]. During the following stages, the soil becomes progressively stiffer and stiffer, while its displacements become slow or extremely slow and the movement type from flow turns to sliding