GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 Site seismic response studies: moving from 2 to 3 dimensions I. Primofiore* 1,2 , G. Vessia 1 , G. Laurenzano 2 , P. Klin 2 1 “G D’Annunzio” University of Chieti-Pescara – INGEO Department 2 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS Introduction In local seismic response (LSR) and microzonation studies, site effects are typically analysed by a two-dimensional numerical analysis along vertical sections in the direction of greatest interest. The basic assumption of the 2D approach is that the model has a cylindrical structure (Fig. 1a). When this assumption is true, a 2D analysis is often preferred over a 3D analysis because it requires much less computational effort. However, there are some cases characterised by complex topographic and stratigraphic geometries where the common use of simplified 2D simulations to approximate 3D seismic behaviour may not be appropriate. Considering the example of Arquata del Tronto hill, struck by the 2016-17 seismic sequence in central Italy, dynamic 3D simulations were performed to better understand the role of geometric and material asymmetry in LSR studies (Fig. 1b). Laurenzano et al. (2019) used earthquake records at temporary seismic stations established after the first main earthquake of the 2016 seismic sequence. Primofiore et al. (2020) created an updated 3D digital model of the area and evaluated the resulting ground motions using 2D and 3D numerical simulations of seismic wave propagation. Finally, Baron et al. (2022) highlighted the combined effect of topography and near-surface heterogeneities on seismic response using 3D simulations of seismic wave propagation.