A multiple rotational slide-earthflow in Southern Apennines: The Pietrapertosa landslide

Landslides of the earthflow type are widespread in the highly fissured stiff clays that outcrop all along the Apennines chain in Italy. A typical feature of such phenomena is the evolutionary mechanism that generally consists in the propagation downslope of highly softened soil bodies, called surges, that display a typical flow style and may involve in the movement further soil masses. The following phase is characterized by a long-lasting slowdown in which the landslide body gradually takes a slide style that may be suddenly interrupted by further phases of reactivation by surging. Due to the difficulty to investigate these highly softened and mobile soil masses, the information about the triggering and evolutionary mechanisms is quite poor and deserves further research. This paper presents some results of a study carried out on the Pietrapertosa landslide during a surging phase.