High-Resolution Deformation Monitoring from DInSAR: Implications for Geohazards and Ground Stability in the Metropolitan Area of Santiago, Chile

Abstract

Large urban areas are vulnerable to various geological hazards and anthropogenic activities that affect ground stability—a key factor in structural performance, such as buildings andinfrastructure, in an inherently expanding context. Time series data from synthetic aperture radar(SAR) satellites make it possible to identify small rates of motion over large areas of the Earth’ssurface with high spatial resolution, which is key to detecting high-deformation areas. Santiagode Chile’s metropolitan region comprises a large Andean foothills basin in one of the most seismically active subduction zones worldwide. The Santiago basin and its surroundings are prone tomegathrust and shallow crustal earthquakes, landslides, and constant anthropogenic effects, suchas the overexploitation of groundwater and land use modification, all of which constantly affectthe ground stability. Here, we recorded ground deformations in the Santiago basin using a multitemporal differential interferometric synthetic aperture radar (DInSAR) from Sentinel 1, obtaininghigh-resolution ground motion rates between 2018 and 2021. GNSS stations show a constant regionaluplift in the metropolitan area (~10 mm/year); meanwhile, DInSAR allows for the identification ofareas with anomalous local subsistence (rates < ?15 mm/year) and mountain sectors with landslideswith unprecedented detail. Ground deformation patterns vary depending on factors such as soiltype, basin geometry, and soil/soil heterogeneities. Thus, the areas with high subsidence rates areconcentrated in sectors with fine sedimentary cover and a depressing shallow water table as well asin cropping areas with excess water withdrawal. There is no evidence of detectable movement onthe San Ramon Fault (the major quaternary fault in the metropolitan area) over the observationalperiod. Our results highlight the mechanical control of the sediment characteristics of the basinand the impact of anthropogenic processes on ground stability. These results are essential to assessthe stability of the Santiago basin and contribute to future infrastructure development and hazardmanagement in highly populated areas