Effects of the Central Italy 2016 seismic sequence on slope stability: preliminary analysis of some major rock slides

The August and October 2016 earthquakes caused several instability phenomena on rock slopes over a large area of the Apennine mountain chain. Major rock slides and rock falls were caused by the October earthquakes, which involved the northern part of the damaged area and surprisingly triggered relevant rock falls in the southernmost part. The distance from inhabited zones and roadways limited the consequences of larger failures with respect to their potential damage. After an overview of the rock instability phenomena, the geological setting of the area and the main features of 2016 earthquakes, selected major rock slides were examined in more detail. In situ and laboratory investigations are described, including UAV models of the slope morphology. Landslide geometry, rock mass structure and instability mechanisms are discussed, stressing critical aspects of their reconstruction. Finally, an attempt is made to link failure mechanisms to geological, structural and joint surface conditions and to features of local seismic motion, in the perspective of better appraising the seismic hazard in the region.