GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.1 GNGTS 2024 We utilised the OpenQuake engine (Pagani et al. , 2014) to then conduct a probabilistic seismic hazard analysis (PSHA) for the region that contains the RETRACE-3D model, using the ASPECT modelling results. The seismic moment rate of each fault was calculated from the total strain rate across the fault surface, which was then used to determine the rate of occurrence of a characteristic, full-fault rupture. Our RETRACE-3D hazard results show a good agreement with the hazard results using the ESHM20 fault model (Danciu et al. , 2021) at low probabilities of exceedance. Finally, disaggregation by source allowed the identification of the faults within the fault system that are the main contributors to the hazard for some representative sites. This innovative PSHA model for the Central Italian Apennines represents one of the first applications of geodynamic finite-element modelling of a highly complex fault system to characterise the 3-D distribution of seismic strain within the subsurface for a hazard analysis. In this contribution, we present preliminary results, recognising that our work to date has revealed plenty of directions for subsequent work to be done. Such future work might include, for example, not only improving the rheology of the various components of the finite-element model but also abandoning the hypothesis of full segmentation. An approach to build a fault-based occurrence model by considering the full set of faults as part of an interconnected system of sections would be similar to the state-of-the-art hazard models in other regions of the world, such as California and New Zealand. References: Bangerth, W., Dannberg, J., Fraters, M., Gassmoeller, R., Glerum, A., Heister, T., Myhill, R., & Naliboff, J. (2022). ASPECT: Advanced Solver for Problems in Earth's ConvecTion, User Manual. https://doi.org/10.6084/m9.figshare.4865333.v9 Buttinelli, M., Petracchini, L., Maesano, F. E., D'Ambrogi, C., Scrocca, D., Marino, M., Capotorti, F., Bigi, S., Cavinato, G. P., Mariucci, M. T., Montone, P., & Di Bucci, D. (2021a). The impact of structural complexity, fault segmentation, and reactivation on seismotectonics: Constraints from the upper crust of the 2016–2017 Central Italy seismic sequence area. Tectonophysics , 810 , 228861. https://doi.org/10.1016/j.tecto.2021.228861 Buttinelli, M., Maesano, F. E., Petracchini, L., D'Ambrogi, C., Scrocca, D., Di Bucci, D., Basili, R., Cara, P., Castenetto, S., Giuliani, R., Salvi, I., Bigi, S., Cavinato, G. P., Di Filippo, M., Messina, P., Castaldo, R., De Novellis, V., Pepe, S., Solaro, G., . . . Ventura, R. (2021b). RETRACE-3D Central Italy Geological Model. Italian Institute for Environmental Protection and Research (ISPRA). https://doi.org/10.13127/RETRACE-3D/GEOMOD.2021 Chiaraluce, L., Di Stefano, R., Tinti, E., Scognamiglio, L., Michele, M., Casarotti, E., Cattaneo, M., De Gori, P., Chiarabba, C., Monachesi, G., Lombardi, A., Valoroso, L., Latorre, D., & Marzorati, S. (2017). The 2016 Central Italy Seismic Sequence: A First Look at the Mainshocks, Aftershocks, and Source Models. Seismological Research Letters , 88 (3), 757-771. https://doi.org/10.1785/0220160221