Crustal mobility analysis in the proximal Andean broken foreland at 31°S: A geodetic and geophysical approach

In this study, we delve into an in-depth analysis of crustal mobility within the broken foreland of the Southern Central Andes, specifically focusing on the proximal area between 31°S and 32°S. This region presently stands as one of the most dynamically evolving and seismically active zones in the extensive Andean retroarc area. To achieve our goal, we employed a multidisciplinary approach encompassing the analysis of gravity data and GNSS measurements. Here, we discuss previous GNSS data and present new measurements, collected from a high-precision geodetic network established along the proximal broken foreland at 31°S latitude. To enhance our findings, we complemented this data with measurements of temporal gravity variations, primarily of tectonic origin, and conducted geophysical modeling of basement structures in the foreland area. Our geophysical model of the upper crust unveiled that deformation is closely associated with basement structures marked by faulted blocks and transverse lineaments identified in previous surface studies. The GNSS data analysis revealed complex crustal mobility patterns that are not easily explained. In general, the integrated analysis highlights varied responses observed in vectors and gravitational changes across distinct crustal domains in the study area that seem to conform to the characteristics of a fragmented or broken foreland setting. This structural configuration allows, to a certain degree, independent movement of crustal blocks. However, it appears that a substantial portion of the fractured foreland exhibits a relatively cohesive behavior, serving as coherent domains that facilitate elastic deformation linked to the underlying deep structures beneath the Eastern Precordillera. Therefore, this study provides further insights into the crustal mobility of broken foreland systems, where far-field tectonic stress interacts with complex basement block structures and intermontane sedimentary depocenters. These findings are of paramount significance in the context of intraplate earthquakes in the Andean broken foreland near San Juan City. Below is a brief description of our study: This investigation conducts an extensive analysis of crustal mobility within the fractured foreland of the Southern Central Andes, focusing specifically on the proximal region between 31°S and 32°S. Positioned within one of the most dynamically evolving and seismically active zones in the extensive Andean retroarc area, the study employs a mu