GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 - POSTER GNGTS 2023 Waveform modeling of moderate earthquakes to improve the comprehension of the seismic structure beneath the southern Apennines M. Scarponi, F. Di Luccio, C. Piromallo Istituto Nazionale di Geofisica e Vulcanologia, INGV, Rome, Italy The Apennines mountain range develops all along the Italian peninsula, presenting important variations in terms of both structural and tectonic environments, and seismogenic patterns as well. This is observed not only along the main NW-SE chain axis, but also by comparing multidisciplinary observations between the western Tyrrhenian and the eastern Adriatic domains. In this work, we focus on the southern Apennines, where the Adriatic plate subducts westward under the thinner Tyrrhenian plate and the highest seismic release is documented. In particular, the western domain is associated with heterogeneous and distributed patterns of CO 2 gas emission at the surface; the latter ceasing in the eastern domain, where high-pressure fluids are trapped in crustal pockets and affect the seismogenic cycle (e.g., Di Luccio et al., 2022). In this framework, we perform regional-scale P- and S-body waveform analysis and forward numerical modeling, for a selected catalog of crustal events recorded by the broadband seismic stations of the permanent national Italian seismic network as well as of temporary passive seismic experiments. We focus on a SW-NE transect, which cross-cuts the southern portion of the Apennines chain, and along which the recorded waveforms exhibit important differences (in terms of frequency content and pulse shape, e.g. Figure 1) between eastward- and westward-directed propagation. Starting from velocity models such as the reference EPcrust (Molinari et al. 2011) and the recent adjoint tomography of Magnoni et al. (2022), we use the finite difference numerical modeling code nbpsv2d (Li et al. 2014) to produce synthetic waveforms to be compared with the observations. By including information on the earthquake source mechanism and by improving the waveform fit in terms of both arrival time and body-wave coda, we provide new information on the crustal structure of the Southern Apennines, aimed at improving our understanding of the fluid-seismicity interaction in the area. This research is performed in the framework of FURTHER project ( https://progetti.ingv.it/en/further ) .