The Celentino deep-seated gravitational slope deformation (DSGSD): structural and geomechanical analyses (Peio valley, NE ITALY)

Deep-seated gravitational slope deformations (DSGSD) are quite common phenomena in the Eastern Italian Alps. The Celentino DSGSD (Trentino-Alto Adige Region, Peio Valley) extends over an area of approximately 5 km2 between 2400 and 1050 m a.s.l., involving metamorphic rocks. A set of parallel ridge-top trenches and antislope scarps are present in the upper part of the slope over a length of 2 km. The shear surface is inferred at 80-100 m in depth, and the involved volume is estimated to be 3.5–4.0 x 108 m3. The displacement of the rock mass has diverted the Noce river for 200–250 m. Structural, geomorphological and engineering geology surveys were conducted both within and outside the DSGSD. The evolution of the whole ridge has been modelled using the 2D finite element code Phase2, simulating the unloading of the glacier cover and assuming a progressive damage of the rock mass. The numerical analyses demonstrate that continuum modelling can be used to examine the evolution of stresses, strains and plastic yielding, providing results consistent with field observations. Structural control due to brittle geological structures seems to be extremely important in the location, shape and extent of the DSGSD and postglacial debuttressing an important predisposing factor in its development and triggering.