GNGTS 2017 - 36° Convegno Nazionale

70 GNGTS 2017 S essione 1.1 Tab. 1 - 2016 central Italy earthquakes with Mw ≥5.5. Earthquake Origin time (UTC) Lat. Long. Depth (km) Mw EMSC n° rec. 24/8/2016 01:36:32 42.704 13.251 7.9 6.2 260 24/8/2016 02:33:29 42.793 13.162 6.8 5.5 190 26/10/2016 17:10:36 42.880 13.128 8.7 5.5 199 26/10/2016 19:18:06 42.909 13.129 7.5 6.1 247 30/10/2016 06:40:18 42.840 13.110 9.4 6.5 235 generally higher than those predicted by the considered relations at short distances, and smaller at distances greater than 100 km. The scatter exceeds 1 standard deviation bound of Ak14 GMPE. For the August 24 earthquake, the strong motion record of Amatrice station (AMT) shows values which largely exceed the Italian code spectrum, both in terms of horizontal and vertical components, in the range of periods corresponding to 2-3 storeys buildings. This fact partially explain the huge and extensive damage suffered by Amatrice buildings Based on the strong motion time histories recorded by the RAN and INGV stations (http:// ismd.mi.ingv.it) , shakemaps of the geometrical mean of the two horizontal components of PGA, PGV, and spectral acceleration values have been implemented in a Geographical Information System (Quantum GIS Development Team 2017) drawing the “isolines” of the values recorded by the stations. In particular the Effective Peak Acceleration (EPA) has been calculated as the mean of the acceleration spectral ordinates in the period range 0.1-0.3 seconds divided by 2.5. This parameter has been considered a good damage indicator because almost 85% of the buildings in Amatrice have 2 or 3 floors. Fig. 1 shows the comparison between the shakemap Fig. 1 - Comparison between the isolines of the macroseismic intensity evaluated after the 24 August earthquake (Galli et al., 2016) and the geometrical mean of the horizontal components of the Effective Peak Acceleration (EPA) calculated as the mean of the spectral ordinates in the periods 0.1-0.3 s. divided by 2.5. (RAN and INGV data).