GNGTS 2016 - Atti del 35° Convegno Nazionale

94 GNGTS 2016 S essione A matrice The major intensities were observed in Pescara del Tronto, Saletta andAmatrice (respectively I EMS 10-11, I EMS 10, I EMS 9-10), which were mainly justified by a diffuse grade 5 of damage to several masonry buildings (Fig. 2). Fig. 2 – Diffused collapses inAmatrice (left) and aerial view of Pescara del Tronto (right, retrieved on www.meteoweb. eu). Up to a radius of about 12 km far from the instrumental epicentre, damages compatible with a I EMS 8 level were observe. In these localities most of the residential masonry building (vulnerability class B) experienced a grade 3 of damage (Fig. 3). The villages of Vezzano, Spelonga and Colle d ’ Arquata (I EMS 6) showed a particular very slight grade of damage (Fig. 3), even if quite close to the instrumental epicentre zone, probably due to some beneficial site effects. Fig. 3 – Large diagonal cracks in most walls (Preta I EMS 8-9, left) and slight damages in Spelonga (I EMS 6, right). The intensity level I EMS evaluation was quite difficult for the centers located in the southeaster area, in the Abruzzo region, since many building were still presenting some effects induced by the 2009 L ’ Aquila earthquake. The low level of ground shaking experienced by this area, together with need of quantify the increment of damages, made the macroseismic intensity assessment quite challenging. Conclusions. This work illustrates the first preliminary results of a macroseismic survey performed in the area hit by the August 24, 2016 Amatrice earthquake and provides the map of the intensity level experienced by 180 localities. The field observations and some of the preliminary results shows the significant influence of site effects for some localities. Finally the particularity of the area in which the earthquake occurred, introduced the problem of dealing with pre-damaged (2009 L ’ Aquila earthquake) and seismically retrofitted residential buildings (1997 Umbria earthquake) for the macroseismic intensity assessment.