Geomorphological Hazard in Active Tectonics Area: Study Cases from Sibillini Mountains Thrust System (Central Apennines)

In many areas of the Umbria-Marche Apennines, evident traces of huge landslides have been recognized; these probably occurred in the Upper Pleistocene and are conditioned by the tectonic-structural setting of the involved Meso-Cenozoic formations, in a sector of the Sibillini Mountains (central Italy). The present work aimed to focus on a geomorphological hazard in the tectonic-structural setting of a complex area that is the basis of several gravitational occurrences in different types and mechanisms, but nonetheless with very considerable extension and total destabilized volume. An aerophoto-geological analysis and geomorphological survey allowed verification of how the main predisposing factor of these phenomena is connected with the presence in depth of an important tectonic-structural element: the plane of the Sibillini Mountains thrust, which brings the pre-evaporitic member of the Laga Formation in contact with the Cretaceous-Eocene limestone lithotypes (from the Maiolica to the Scaglia Rosata Formations) of the Umbria-Marche sedimentary sequence. Another important element for the mass movements activation is the presence of an important and vast water table and related aquifer, confined prevalently by the different structural elements and in particular by the thrust plane, which has acted and has continued to act, weakening the rocky masses and the overlaying terrains