CONICET | Buscador de Institutos y Recursos Humanos

On January 18, 2021, a moderate earthquake (Mw 6.5) occurred ~ 45 km southwest of San Juan, a city in Central-WesternArgentina, at a relatively shallow depth of ~ 20 km. The earthquake caused damage to the environment and infrastructurein the affected area, which is home to ~ 600,000 residents. To assess ground deformation, identify the seismogenic source,and evaluate the extent of secondary effects, we utilized Differential Synthetic Aperture Radar Interferometry (DInSAR)techniques in combination with Sentinel-2 visible and infrared imagery, as well as field data. DInSAR results suggestedcentimeter-scale ground deformation around the epicenter, off-fault deformation linked to regional structures, and site effects,such as liquefaction and landslides. By combining the values extracted from a 3-year-long PSI and SBAS time series, weestimated a vertical displacement of approximately 4.5 cm near the epicenter. Off-fault deformation involves some degree ofground settling on top of a blind or buried section of the Papagallos fault system, the reactivation of a section of the Rinconadafault system, and liquefaction and ground settling processes in the Tulum Valley. Rockfalls were distributed throughout ageologically diverse terrain and along a NW swath, with their occurrence controlled by the shaking intensity. The totalarea affected by secondary effects was ~ 3800 km2.Based on the available focal mechanism solutions and the distributionof environmental damage, we propose a left-lateral strike-slip displacement in a blind NW-striking fault, although differentinterpretations are discussed. Finally, we estimated the epicentral depth from SBAS time series Bayesian Inversion and fromdifferential travel times pP-P, obtaining a depth of 2025 km.

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