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

2000; Sobolev & Babeyko, 2005; Martinod et al., 2020). In the Pampean flat-slab segment, located between 27° and 33°S, the Nazca Plate subducts towards the east, at an angle of 5-10° (i.e., approximately “flat”; Barazangi & Isacks, 1976) under the South American Plate, producing a high coupling of plates (Gutscher, 2002). However, to the south, it subducts at an angle of ~30° (e.g., Gutscher et al., 2000; Anderson et al., 2007). The upper crust of the upper plate along the flat subduction segment shows evidence of long-term contractional deformation starting in the early Miocene to the present (e.g., Cristallini & Ramos, 2000; Charrier et al., 2007; Jara & Charrier, 2014; Rodríguez et al., 2018; Estay et al., 2023). Between 32.5° and 33°S, the western edge of the Principal Cordillera is defined by a topographic rupture coinciding with an old west-vergent thrust fault, the Pocuro structural system (e.g., Rivano, 1996; Rivano et al., 1993), which limits the Principal Cordillera with the Los Andes-San Felipe Depression (Fig. 1). South of 33°S, the western edge of the Principal Cordillera, the West Andean Thrust front, is defined by its border with the Central Depression (Fig. 1; e.g., Charrier et al., 2007; Armijo et al., 2010; Farías et al., 2010). A series of works developed on the Pocuro structural system has partially revealed the characteristics of its Quaternary faults (Troncoso, 2014; Medina, 2018; Estay, 2019; Figueroa et al., 2021; Taucare et al., 2022; Quezada, in progress), but critical parameters for seismic hazard characterization, such as the age and slip rates of recent faulting are just becoming known. In this abstract, we outline the initial progress in understanding the paleoseismicity associated with the Quaternary faults (Cariño Botado Fault System, CBF) of the Pocuro structural system, which has already been discussed in a recent publication (Estay et al., 2023). Fig. 1: SRTM DEM (NASA-JPL, 2013) image with the study region’s main structural systems (Taken from Estay et al., 2023; data references therein cited). Location in South America is indicated in a black dot. The boundaries of the regional features are indicated by the segmented white line (FC, Frontal Cordillera; CC, Coastal Cordillera; PC, Principal Cordillera; CD, Central Depression; LASFD, Los Andes-San Felipe Depression). Abbreviations: LF, Llimpo Fault; CMS, Chincolco-Las Minillas Structural System; PSS, Pocuro Structural System; LAS, Los Ángeles Structural System; IF, Infiernillo Fault (Cerro Renca and Portezuelo de Chada Faults); EAF, El Arrayán Fault; SRF, San Ramón Fault; LA Creek, Los Ángeles Creek; LM, Las Minillas. The location of the principal localities closest to the structural study systems is indicated, highlighting the large, populated area of the metropolis of Santiago (gray area), with ~6 million inhabitants. The red box indicates the location of Fig. 3.