Reconnaissance of geotechnical aspects of the 2016 Central Italy earthquakes

Between August and November 2016, three major earthquake events occurred in Central Italy. The first event, with M6.1, took place on 24 August 2016, the second (M5.9) on 26 October, and the third (M6.5) on 30 October 2016. Each event was followed by numerous aftershocks. The 24 August event caused massive damages especially to the villages of Arquata del Tronto, Accumoli, Amatrice, and Pescara del Tronto. In total, there were 299 fatalities, generally from collapses of unreinforced masonry dwellings. The October events caused significant new damage in the villages of Visso, Ussita, and Norcia, although not producing fatalities, since the area had largely been evacuated. The Italy–US Geotechnical Extreme Events Reconnaissance team investigated earthquake effects on slopes, villages, and major infrastructures. The approach adopted to carry out post-earthquake reconnaissance surveys was to combine traditional reconnaissance activities of on-ground evidences and mapping of field conditions with advanced imaging and damage detection routines enabled by state-of-the-art geomatics technology. Presented herein are the outcomes of the post-event reconnaissance surveys conducted after both the August main shock and the October events, focusing on geotechnical aspects, such as earthquake-triggered slope failures, mud volcanoes, performance of different geotechnical structures (i.e., dams, retaining walls, rockfall barriers, road embankments) and building damage patterns related to site amplification.