Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

The Pampean segment (27-33.5°S) of the Andean backarc, which is the focus of this study, is one such region characterized by numerous shallow-focused seismic events and the reactivation of basement faults, extending far inland to approximately 700 km from the Peru-Chile trench boundary (Ramos, 1988) (Fig. 1). Within the Pampean segment, the two major cities, San Juan and Mendoza, are located 300 km east of the plate boundary with a total population of approximately 1.7 million. The region has experienced a total of 8 earthquakes in the last two centuries (Alvarado & Beck, 2006; Ammirati et al., 2022). Some of the shallow and impactful events include the Mw 7.0 1861 Mendoza earthquake, the Mw 7.4 1944 San Juan earthquake, the Mw 7.5 1977 double Caucete earthquakes and the most recent Mw 6.5 2021 earthquake once again in San Juan (Kadinsky-Cade et al., 1985; Alvarado & Beck, 2006; Meigs & Nabelek, 2010) (Fig. 1a). Fig. 1: Regional map of the Precordillera fold and thrust belt with a zoom to the Marquesado Fault/Trench area within the RIM22 military base. Major cities San Juan and Mendoza are demarcated, epicenters are represented by red stars for 3 major earthquakes within the region, mapped faults with their corresponding dip direction are marked, subdivisions of the Precordillera are given colored polygons, and important faults are marked as 1, 2, and 3. 1 is the Zonda Fault, 2 is the Marquesado Fault, and 3 is the Marquesado Fault Group.