Abstract
We report the first detection of unrest at Socompa, Northern Chile, a
stratovolcano which has recorded no eruptions since
~7,200 years ago. We measure deformation at and around
Socompa using Interferometric Synthetic Aperture Radar (InSAR)
observations between Jan 2018 and Oct 2021. We find that, whilst
initially inactive, Socompa shows a steady uplift (17.5 mm/yr) from Dec
2019, independently recorded by near-field continuous Global Positioning
System (GPS) data. The data can be fit with pressure increase in an
ellipsoidal source region stretching from 1.9 to 9.5 km, with a volume
change rate of ~5.8×106 m3/yr. Our observations of the
onset of uplift preclude the possibility that a nearby Mw 6.8 deep
intraslab earthquake on 3rd 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.