Selection of the seismic input for site response numerical simulations within the seismic microzonation in the Apulian region

Seismic Microzonation (SM) studies are ongoing in the Apulian region, where seismic hazard depends on two types of active seismogenic structures: 1) autochthonous faults, mainly located in northern Apulia, capable of causing highly energetic earthquakes with rather long return times; 2) tectonic structures located in neighbouring regions, which can generate very strong earthquakes. This region presents a considerable heterogeneities of site conditions due to different geological-structural domains: orogenic belt (Daunia Mounts), foredeep (Tavoliere Plain) and foreland (Gargano, Murge). This geologic variability implies a heterogeneity of seismic scenarios potentially capable of affecting local seismic hazard. The site response properties can be obtained by numerical simulations that require the selection of waveforms to be used as seismic inputs. Accelerometric databases collect real waveforms for a variety of seismic scenarios, however often not representative of the studied area; so we combined real and synthetic accelerograms. In this paper we propose an approach to optimise the selection of the seismic inputs for seismic response numerical simulations. The results of the first tests of its application appear promising and the method will be implemented in the third level studies of SM planned for the Apulia region.