Deformation observations and geodetic modelling during the recent unrest at Askja volcano

At the beginning of August 2021, inflation was detected at Askja volcano, on a continuous GNSS station located to the west of Öskjuvatn and on interferograms generated using data from four separate Sentinel-1 tracks. Ground deformation measurements at Askja commenced in 1966 with levelling observations and since this time additional ground monitoring techniques have been employed, including GNSS and Satellite interferometry (InSAR) to detect long-term changes. Ground levelling measurements undertaken between 1966-1972 revealed alternating periods of deflation and inflation. Measurements from 1983-2020 detailed persistent subsidence of the Askja caldera, initially at an inferred rate of 7 cm/yr, decaying in an exponential manner. Suggested explanations for the long-term subsidence include magma cooling and contraction, or withdrawal of magma – eventually facilitated by an extensive magma-rich plumbing system, with an open conduit between the uppermost and the deeper parts of the magmatic system. This presentation will focus on the recent period of uplift and provide an overview of the GNSS and InSAR observations to date and present the latest geodetic modelling results which describe the best-fit source for the observed deformation.