GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione A matrice 93 The building stock is also composed by recently retrofitted masonry structures (mostly renovated after the 1997 Umbria earthquake, to which a vulnerability class D was assigned) and seismically designed reinforced concrete frame buildings (vulnerability class C). Industrial warehouses are not included in the EMS98 scale since they are not considered representative for the intensity value assessment, anyway the surveyed area is mostly mountainous without the presence of significant industrial zones. Intensity assessment and discussion of results. The 2016 Amatrice seismic sequence was characterized by one severe mainshock (1:36 UTC, M w 6.0), and subsequently by only one relevant aftershock (2:33 UTC, M w 5.3): as a consequence, the observed intensity map can reasonably be seen as the effects of a seismic scenario. According to the EMS98 scale and assessing method, the intensity values for each locality was established on the basis of the damage grades detected on the different vulnerability classes. In some localities, troubles on the evaluation of the I EMS intensity were detected, mainly due to the different grade of damage suffered by old stone-masonry residential buildings and reinforced concrete or retrofitted masonry structures. According to Galli et al. (2009), effects recorded by the building inside the old city centers were considered more reliable for a proper intensity assessment. Fig. 1 shows the surveyed localities with the observed macroseismic intensity I EMS . Fig. 1 – Macroseismic IEMS intensities observed for the 2016 Amatrice seismic sequence (cumulative damage up to September 6, 2016).