Exploring complex normal faulting systems through physics-based dynamic rupture modeling

Hugo Samuel Sánchez Reyes (1) , O. Scotti (1) , Sebastien Hok (1) , Alice-Agnes Gabriel (2) , Carsten Uphoff (2)

1 IRSN/PSE-ENV/SCAN/BERSSIN - Bureau d'évaluation des risques sismiques pour la sûreté des installations
2 LMU - Institut für Informatik [München/Munich]

Complex earthquake ruptures involving multiple fault segments represent an increasingly well observed, but yet not well-accounted for, seismic hazard for the populations living in proximity to active fault systems. Therefore, it is crucial to estimate the potential of complex, multi-fault earthquake ruptures to occur in any given region and to develop physics-based proxies of fault connectivity or rupture "jumping tendency". In this study, we specifically tackle the challenge of better understanding the conditions which could promote multi-fault earthquake ruptures in the Central Apennines, Italy. The study of this area, where the 2016 Amatrice-Visso-Norcia earthquake sequence occurred, is of great importance to unveil the mechanisms and physical conditions which impeded a more hazardous larger single rupture instead of the complex months-lasting sequence. To enhance our understanding of this fault system (i. e Laga, Monte Vettore and associated subfaults), we take advantage of recently published data such as the Fault2sha Central Italy fault database, relocated seismicity, fault damage studies and an integrated 3D crustal model. Our earthquake models focus on normal fault systems, which are characterized by different stress conditions in comparison to previous studies which geared more towards understanding strike-slip or reverse faulting environments. Our goal is to answer key questions which can enhance probabilistic hazard estimates in a physics-based sense, such as: 1) how do normal faults interact during dynamic rupture propagation? 2) how do free-surface effects, and/or other physical conditions, promote step-over rupture jumps? For these purposes, we use SeisSol (www.seissol.org; e.g., Wollherr et al., 2018; Ulrich et al., 2019) to simulate physics-based rupture scenarios taking into account complex geometries (i.e. listricity, roughness and plasticity), regional stress fields, cataloged seismicity and mapped and interpreted active faults. Our results are inscribed within the "EQ-Time" ANR Project (French National Research Agency) whose goal is to quantify the temporal and spatial slip variability in the Central Appenines earthquake cycle spanning months to million years timescales

Domaines: Géophysique [physics.geo-ph]

Hugo Samuel Sánchez Reyes, O. Scotti, Sebastien Hok, Alice-Agnes Gabriel, Carsten Uphoff. Exploring complex normal faulting systems through physics-based dynamic rupture modeling. AGU fall meeting 2021, AGU, Dec 2021, New Orleans (LA), United States. pp.S51C-03. ⟨irsn-04095326⟩