GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 The hydrogeological response of the Sibillini Mts. carbonate aquifer to the M w 6.5 Norcia earthquake: conceptual model and numerical analysis E. Zullo 1 , M. Albano 2 , M. Saroli 1,2 , M. Moro 2 , G. Testa 1 , N. Bonora 1 , M. Petitta 3 , C. Doglioni 2,3 1 Dipartimento di Ingegneria Civile e Meccanica, Università degli Studi di Cassino e del Lazio meridionale 2 Istituto Nazionale di Geofisica e Vulcanologia INGV-Roma 3 Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza” Introduction Because of their complex architecture and in relation to the variability of physical parameters and geological factors, it is notoriously difficult to adequately characterize the hydrologic behavior of fault zones within the Earth’s crust. The estimation of the hydraulic properties of fault zones remains a challenge and the lack of data, related to the inability to obtain direct measurements especially in depth, represents an important gap in hydrogeological modeling. Fault zones can generally act as hydraulic conduits, barriers, or combined conduit-barrier systems, depending on the different relative permeability between fault core and damage zone and as a function of the stress and strain conditions (Caine et al ., 1996; Bense et al ., 2013). Since the Earth’s crust can be considered a biphasic medium, consisting of a solid skeleton and voids filled with fluids (Fyfe, 2012; Albano et al ., 2019) with a poroelastic behavior (Biot, 1941; Wang, 2000; Albano et al. , 2019), the stress variations induced by a seismogenic fault rupture can change the hydrologic properties of the crustal rocks; thus changes in rock permeability and fluid mobility are expected following an earthquake (Manga et al ., 2012; Manga & Wang, 2015). A general increase in bulk permeability occurs after an earthquake, due to several mechanisms related to the dynamic stress caused by the seismic waves propagation, which include the fracture cleaning effect induced by the pore pressure increase. The “aquifer fault rupture” is a further interpretative mechanism to explain the aquifer response to earthquakes (Manga et al ., 2012; Manga & Wang, 2015; Mastrorillo et al ., 2020; Saroli et al ., 2022): the seismogenic fault rupture