geosciences Article Post-Collapse Evolution of a Rapid Landslide from Sequential Analysis with FE and SPH-Based Models Lorenzo Brezzi 1,* , Edoardo Carraro 1, Davide Pasa 1, Giordano Teza 2, Simonetta Cola 1 and Antonio Galgaro 3 1 Department of Civil, Environmental and Architectural Engineering, University of Padova, via Ognissanti 39, 35129 Padova, Italy;
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[email protected] (S.C.) 2 Department of Physics and Astronomy “Augusto Righi”, Viale Carlo Berti Pichat 6/2, 40127 Bologna, Italy;
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[email protected]; Tel.: +39-0498277992 Abstract: Propagation models can study the runout and deposit of potential flow-like landslides only if a reliable estimate of the shape and size of the volumes involved in the phenomenon is available. This aspect becomes critical when a collapse has not yet occurred and the estimation of the unstable volume is not uniquely predictable. This work proposes a strategy to overcome this problem, using two established analysis methods in sequence; first, a Strength Reduction Method (SRM)-based 3D FEM allows the estimate of the instable volume; then, this data becomes an input for a Smoothed Particle Hydrodynamics (SPH)-based model. This strategy is applied to predict the possible evolution of Sant’Andrea landslide (North-Eastern Italian Alps). Such a complex landslide, Citation: Brezzi, L.; Carraro, E.; Pasa, which affects anhydrite–gypsum rocks and is strongly subject to rainfall triggering, can be considered D.; Teza, G.; Cola, S.; Galgaro, A.