Terrain Subsidence in the Salar de Olaroz (Jujuy, Argentina) Caused by Lithiferous Brine Extraction, Detected by Multi-Temporal SAR Interferometry

Salar de Olaroz located in the Puna Jujeña is one of the salines in Argentina where several large mining projects of brines extraction for lithium production are concentrated. This activity involves the creation of large drilling parks for pumping underground brine. As the projects have been in production for several years, a multi-temporal SAR interferometry assessment was carried out to detect possible ground subsidence associated with this mining activity. At the Alaska Satellite Facility (ASF) platform, Sentinel-1 images were processed with the Vertex SBAS tool to generate vertical displacement maps, which resulted in a mapping of cumulative displacements. This leads to detected areas within the salar that show marked patterns of subsidence, concentrated around the drill batteries. The cumulative change values for the period analyzed (2018-2020) range from +12 cm to −17 cm, with an annual rate of progression of between +4 cm to −5 cm, with the maximum subsidence always coinciding with the position of the boreholes. Additionally, control points were used to validate the results, one located within the salar but outside the pumping fields and another which belongs to the IGN's Argentinean high precision geodesic network, where in both the variation measured over time was zero.