The 2016 Central Italy earthquake sequence: observations of incremental building damage

A sequence of normal-fault earthquakes occurred between the end of August 2016 and the end of October 2016 in central Italy causing significant damage and major disruption in a wide area covering several municipalities across four regions, Abruzzo, Lazio, Marche, and Umbria. The sequence of events is composed of five events with magnitude greater than Mw5, two of which with magnitude greater than Mw6. The last October event is the strongest event since the 1980 Italian Irpinia event. The building portfolio in the affected area was not particularly resistant to intense ground shaking, resulting in the collapse and heavy damage of several buildings and in tens of thousands of homeless. To study the damage induced by the earthquakes sequence, two international missions were organized by the Geotechnical Extreme Events Reconnaissance (GEER) group after the first and the last seismic event. The consistent and detailed inspection of structural damage to buildings after a single and a sequence of events, constitutes a precious case study for examining the evolution of structural damage of different structural systems to a series of ground motions. It further underlines the high vulnerability of a part of the Italian building stock, especially under multiple shocks, and opens the floor for discussing the design implications of cumulative damage.