GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.2 GNGTS 2024 TesHng syntheHc site amplificaHon maps through comparison with empirical esHmates in Central Italy S. Hailemikael 1 , G. Cultrera 1 , C. Barnaba 2 , G. Laurenzano 2 , G. MarHni 1,3 , A. Peloso 3 , F. Cara 1 , G. Di Giulio 1 , D. Famiani 1 1 Is9tuto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy. 2 Is9tuto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy. 3 Agenzia Nazionale per le Nuove Tecnologie, l’Energia e lo Sviluppo Economico Sostenibile (ENEA), Frasca9, Italy. In the framework of the naConal research project SERENA - Mapping Seismic Site Effects at REGional and NATIONAL Scale, the work package 6 (WP6) aims to test the ground moCon amplificaCon maps developed within the project by means of empirical esCmates. The target maps will be mainly generated by a hybrid geological-geomorphological classificaCon of the naConal territory and stochasCc 1D equivalent linear numerical simulaCons (syntheCc approach) based on seismic microzonaCon data collected over the last decade (Moscatelli et al. , 2020). To this end, we collected and enriched the database of experimental site-specific amplificaCon esCmates originally gathered by Priolo et al . (2020) for Central Italy and compared these esCmates with those obtained in a study preceding this project by implemenCng a syntheCc approach similar to what will be developed in SERENA (Falcone et al. , 2021). In parCcular, the empirical esCmates for about 240 seismic monitoring sites in Central Italy were obtained by evaluaCng more than 45000 seismic records processed with a standardised approach to derive site amplificaCon factors (FA). The FA values are calculated within three period intervals, defined by the current seismic microzonaCon guidelines (SM Worging group 2015) and representaCve of short, medium and long period ground-moCon amplificaCon (namely 0.1s-0.5s, 0.4s-0.8s, 0.7s-1.1s). We calculated and compared the staCsCcal distribuCons of experimental and syntheCc FA (FA_exp and FA_syn, respecCvely) for the 240 sites in Central Italy, also by means of specifically developed GIS tools. We found that the FA_syn distribuCons are within the range 1-2 for all considered periods, while all FA_exp distribuCons have median values equal to or greater than 2 and large upper tails, with amplificaCon values up to 7.5. The distribuCon of FA_exp also shows values below 1 for a few sites, indicaCng de-amplificaCon compared to the considered reference moCon. The distribuCons of the residuals between FA_exp and Fa_syn (in natural logarithmic units) were then evaluated for each considered site and the influence of the period interval and the