New insights on the tectonic structure of the Southern Central Andes – Western Argentina – from seismic tomography

Abstract

The geodynamic evolution of central Chile-Argentina is mainly controlled by the subduction of the oceanic Nazca plate beneath the continental South American lithosphere. In particular, between 29°S and 34°S, the Nazca plate exhibits a flat-slab subduction around 100 km of depth, that extends eastward for hundreds of km before returning to a downward descent. This condition causes an interruption in the Andean volcanic arc and an intense crustal deformation that continues toward the craton, beyond the foreland thrust belt. The outcome is a very active crustal seismicity and complicated structural framework. In order to study the seismotectonic characteristics of this flat-slab region, we analyzed data recorded by a local network, performing a simultaneous inversion of both the velocity structure and the hypocentre parameters. The availability of accurate hypocentre locations and finely tuned velocity distribution allows us to improve the earthquake source characterization and the knowledge on the ongoing seismotectonics of the region.