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

Abstract

Abstract Deep-seated gravitational slope deformations (DSGSDs) are fairly common phenomena in the Eastern Italian Alps. The Celentino DSGSDs (Trentino–Alto Adige Region, Peio Valley) extends over an area of approximately 5 km 2 between 2400 and 1050 m a.s.l. (metres above sea level), 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 3.5×10 8 –4.0×10 8 m 3 . 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 DSGSDs. The evolution of the whole ridge has been modelled using the two-dimensional (2D) finite element code Phase 2 , 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 DSGSDs, and post-glacial debuttressing an important predisposing factor in its development and triggering. The DSGSDs are common phenomena in areas of high relief energy, associated with orogenic history and mountain unroofing where tectonics is still active.