An application of EMS98 in a medium-sized city: The case of L’Aquila (Central Italy) after the April 6, 2009 Mw 6.3 earthquake

Abstract

This paper describes the damage survey in the city of L’Aquila after the 6 April 2009 earthquake. The earthquake, whose magnitude and intensity reached Mw=6.3 and Imax=9–10 MCS, struck the Abruzzi region of Central Italy producing severe damage in L’Aquila and in many villages along theMiddle Aterno River valley. After the event, a building- to-building survey was performed in L’Aquila downtown aiming to collect data in order to perform a strict evaluation of the damage. The survey was carried out under the European Macroseismic Scale (EMS98) to evaluate the local macroseismic intensity. This damage survey represents the most complex application of the EMS98 in Italy since it became effective. More than 1,700 buildings (99% of the building stock) were taken into account during the survey at L’Aquila downtown, highlighting the difficult application of the macroseismic scale in a large urban context. The EMS98 revealed itself to be the best tool to perform such kind of analysis in urban settings. The complete survey displayed evidence of peculiar features in the damage distribution. Results revealed that the highest rate of collapses occurred within a delimited area of the historical centre and along the SW border of the fluvial terrace on which the city is settled. Intensity assessed for L’Aquila downtown was 8–9 EMS.