First onset of unrest at Socompa: A Recent Geodetic Survey at Central Andean volcanoes in Northern Chile

We report the first detection of unrest at Socompa volcano during our recent survey of Central Andean volcanos in Northern Chile using Interferometric Synthetic Aperture Radar measurements spanning January 2018 to October 2021. We find that Socompa volcano, whilst initially undeforming and no recorded eruptions for 7.2 kyr, shows a steady uplift (17.5 mm/yr) from November 2019, independently recorded by near-field continuous Global Positioning System data. The deformation pattern can be fitted with pressure increase in an ellipsoidal source region stretching from 2.1 to 10.5 km, with a volume change rate of ∼6.2 × 106 m3/yr. Our observations of the onset of uplift suggest it is unlikely that a nearby Mw 6.8 deep intraslab earthquake on 3 June 2020 triggered the unrest. The deformation signal we detect indicates the initiation of unrest at Socompa, after at least two decades without measurable deformation, and many thousands of years without volcanic activity.