GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Do parallel actve fault systems dream of Coulomb Stress Transfer? A. Galderisi 1,2 , P. Galli 3,2 , E. Peronace 2 1 Dipartmento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi di Napoli, Federico II, Italia 2 CNR-IGAG, Roma, Italia 3 Dipartmento Protezione Civile, Roma, Italia Introducton . In this work, we have applied diferent analytcal methodologies in order to explore the modes of frontal transfer of statc Coulomb stress between various seismogenic fault systems. We started from the observaton of a series of surface ruptures formed along the Norcia fault system (NFS) following the Mw 6.6 event of 30 October 2016. The 2016 sequence was not generated by the NFS, but from the Monte Vetore fault system (MVFS). Since the seismological data relatng to this sequence (Chiaraluce et al, 2017; Improta et al, 2019) did not highlight any signifcant event associable to the NFS, we questoned the nature of these ruptures and the possible interacton between these two parallel fault systems. Firstly, a geological-structural survey was conducted along the entre NFS, mapping the coseismic ruptures and calculatng the slip- vector. Then we calculated the change in Coulomb stress produced by the MVFS following the October 30 event. As a result, part of the statc Coulomb stress was transferred from the MVFS to the NFS. We then compared paleoseismological data coming from the two fault system trying to understand whether these fange systems also interact over tme. Finally, the same analysis methodology was applied to the seismogenic fault systems of the Gran Sasso (GSFS) and the Upper Aterno Fault System (UAFS). Geological and seismotectonic framework. The MVFS and the NFS are two seismogenic normal fault systems that extend parallel for over 30 km in the N160° directon, at a distance of ~10 km from each other. Both are actve in historical tmes, with evidence of surface ruptures at least throughout the Holocene (Galli et al, 2018 and 2019). Similarly, the GSFS and the UAFS are two seismogenic fault systems, located ~14 km distant. The GSFS shows a N120° directon, in the north and central sector, while NNW-SSE in the southern sector. Diferently, the UAFS shows a unique master fault directon N160° (Galli et al, 2010; 2011 and 2022). The return tmes calculated from paleoseismological studies are ~1.8 kyr for the MVFS and NFS (Galli et al, 2018; 2019; Tab. 1), with a slip rate of 1.3 mm/yr and 1.2 mm/yr respectvely. While the return tmes of the GSFS is 2.8 + 0.5 ky and of the UAFS 1-2 kyr (for large magnitude events), with a slip rate of 1.8 mm/yr for GSFS and 0.58 mm/yr for UAFS (Galli et al, 2010; 2011 and 2022, Tab. 1).