GNGTS 2015 - Atti del 34° Convegno Nazionale

procedure) as well as a complete wavefield model. A good agreement between experimental and theoretical curves, which is shown in Fig. 2, was obtained with the profile in Tab. 3, which is assumed as representative of the PGL station site. Fig. 2–Results,with respect theHVSR curve representative of the “PGL” station site, of the manual adjustment of the resulting stratigraphical profile, by using both a full-wavefiled and a surface-wave approximation models. Tab. 3 - Seismo-stratigraphical profile under the accelerometric station PGL. depth (m) thickness (m) V S (m/s) lithology geological unit 5 5 220 marl and clay marls (Colombacci) FCO 35 30 410 gypsum GES 65 30 950 marl FAM1c 140 75 1000 sandstone and marl FAM1 In terms of NTC (2008) seismic classification, the site where the “PGL” station lays is a class C soil type, being the V S,30 value (obtained by results of Tab. 3) lower than 360 m/s. The deconvolution process was realized by using 4 accelerograms and the variability intervals shown, in the shallower part, in Fig. 1, as above explained. Statistics about peak ground acceleration (PGA) and acceleration spectral amplitude (SA) at 0.15, 1 and 2 s have been extracted, based on an ensemble of 100 deconvolution runs for each earthquake record. For each earthquake, the two horizontal components have been considered separately, taking into account both the geometric mean and the maximum of PGA and SA of each run. Then the median and the 75 th percentile of the ensemble have been computed. An example of the obtained results is reported in Tab. 4. Tab. 4 - Results for the station of Peglio: 75th percentile of PGA and SA values are reported for the maximum of horizontal components; surface values are derived from the accelerometric registrations, while bedrock values are derived from equivalent linear analysis with STRATA; in the last column is reported the ratio between each couple of values. earthquake event surface (cm/s 2 ) bedrock (cm/s 2 ) surface / bedrock PGA IT-1997-0006 67.959 38.812 1.751 SA at 0.15s IT-1987-0003 164.027 91.022 1.802 SA at 1s IT-1997-0006 19.591 16.960 1.155 SA at 2s IT-1997-0006 8.350 8.001 1.044 GNGTS 2015 S essione 2.2 153