1-D velocity model from local earthquake localization and receiver functions for the southern Neuquén basin: Insights into lithosphere structure and dynamics

Abstract

Knowledge of the lithospheric structure is key to understanding the seismotectonic characteristics of convergent margins. In this study, we provide a robust one-dimensional velocity model for the Añelo region, located within the Neuquén extensional basin in Argentina, with the aim of illuminating the lithospheric characteristics of the back-arc region of the southern central Andes. Data from a temporary network of broadband stations operational from October 2014 to March 2020 was utilized. We employed two distinct seismological techniques for obtaining models with varying resolutions at multiple scales and depths. On the one hand, upper thin layers were obtained by the inversion of a model based on hypocenters from local earthquakes, and on the other, we calculated receiver functions to estimate thicker and deeper layers. By combining both methods we were able to obtain a joint and accurate velocity model, a crucial tool for conducting seismicity studies in the region and achieving precise determinations of earthquake locations. Moreover, the analysis of velocity variations offers valuable insights into the complex lithospheric structure beneath the study area, shedding light on the poorly understood seismotectonic activity in the Andean retroarc. We suggest that the presence of a weakened or hot lithospheric mantle beneath the southern Neuquén Basin may be linked to the Payenia mantle anomaly. This anomaly likely softens the upper plate, concentrating deformation and intraplate seismicity, as documented in the vicinity of the study area.