Gravitational morphogenesis of the Apennine chain in Central Italy.

Systematic geomorphologic analysis of the Umbria-Marche area allows to recognise a noticeable amount of deep-seated gravitational deformations and large-scale landslides. Complexively, some 500 phenomena have been individuated. In the area, the main genetic factors of these phenomena are the following: a) bedrock geology is characterised by high thickness of massive calcareous and arenaceous rocks overlying levels less resistent or thinly stratified with thin pelitic intercalations; b) structure derives from Neogene compressional tectonics to wich strong residual stresses and potential slipping surfaces along tectonic planes are connected; c) extensional tectonics originated high fault scarps which sometimes brought to the surface potential deep sliding planes, whilst compressional tectonics, still active along the coast, is producing folding along whose eastern sides huge gravitational phenomena can take place; d) the area recently underwent a strong uplift, mostly along the axial belt of the Apennines, where the presence of resistant rocks allowed the creation of high and steep slopes bordering either deep transversal valleys or overthrust fronts; e) seismicity is quite high, mostly along the chain axes and, subordinately, along the Adriatic coast .