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

240 PATA Days 2024 R E S U LT S A N D D I S C U S S I O N In Figure 4, a sketch of the main outcrop is shown. From the base to the top in the hanging wall (Figure 4, to the left of the fault core), we observed stratified shales with intercalations of tuffs approximately four meters thick (strike /dip = N17O/53E), followed by a thick and concordant succession of andesitic lithic tuffs, at least four meters thick, and finally, a layer of soil overlying by angular unconformity the tuffs. In the foot wall (to the right of the fault core; Figure 4), sub horizontal layers of about two meters thickness of unconsolidated deposits can be observed, composed of poorly sorted, matrix-supported, with angular clasts gravel-to-block size conglomerates and breccia (Figure 4), with an approximately two meters thick layer of poorly sorted, sandy sediments in the middle. At the fault contact we observed a fault breccia characterized by angular, poorly sorted gravel-to- block- size clasts with a sand-to-clay-sized matrix (Figure 4). This breccia is identified as the fault core zone of the main fault, in which the stratified rocks of the hanging wall are overthrusting the more recent unconsolidated layers of the footwall block. We associate the volcanic rocks in the hanging wall to the Abanico Formation, which outcrops are in the western margin of the Andes in central Chile (e.g. Armijo et al., 2010). Structurally, the stratification of the volcanic rocks in the hanging wall averages a strike/dip of N17O/49E. Additionally, a slight but noticeable tilting of the stratification was observed once approaching the fault core (Figure 3), with the dip ranging from approximately 55° at the fault core Fig. 2: Map of the study area. The main outcrop for this study (Figure 4) is indicated at point 1. The point 2 indicate another smaller outcrop (not shown).