Analysis of major rock slides that occurred during the 2016–2017 Central Italy seismic sequence

The 2016 Italian seismic sequence was characterized by three main shocks that occurred on August 24th, on October 26th and 30th. The latter, a Mw 6.5 event, is the strongest seismic event recorded in Italy since the 1980, Mw 6.9 Irpinia Earthquake. In this time span between the first and the third shock of the 2016 sequence, more than 1000 seismic events of Mw greater than 3.0 and shallow hypocentral depth between 7 and 11 km were recorded, triggering more than of 1300 observed landslides. In this paper, the identification of the triggering models for four selected rock slides was performed together with the mechanical characterization of the affected rock masses both in situ and in laboratory. Large scale morphostructural setting was analysed to verify the role of regional tectonics in the failures. Discontinuity sets were identified at detail-scale using three-dimensional (3D) point clouds developed from structure from motion (SfM) reconstruction using unmanned aerial vehicles (UAVs). In situ and laboratory tests coupled to data from UAV 3D models were used for geomechanical characterization. Data were finally adopted as input of limit equilibrium static analyses, which allowed a better comprehension of the stability conditions prior to seismic events and clarify some aspects of the mobilized strength.