The role of shear surface geometry in the definition of deep-seated gravitational slope deformation thresholds

Deep-Seated Gravitational Slope Deformations (DSGSD) often involve complex kinematic behaviors that may vary spatially and temporally. The Alpine area counts several DSGSDs involving volumes of millions of cubic meters. In this paper we present the case study of Spriana landslide, a common example of DSGSD located in the North of Italy. Geological, geophysical and topographic investigations have been combined to develop an accurate physical model of the slope. However, some issues still need to be tackled and the definition of a reliable triggering threshold is yet a challenge. Our work focuses on the importance of the shear surface geometric features for threshold definition. We performed several 3D numerical simulations addressing the definition of groundwater table critical level. We believe our findings may improve the early warning system of Spriana landslide and we think that our approach should be used to address other complex deep seated gravitational slope deformations.