2021–2023 Unrest and Geodetic Observations at Askja Volcano, Iceland
Michelle Parks, Freysteinn Sigmundsson, Vincent Drouin, Sigrún Hreinsdóttir, Andrew Hooper, Yilin Yang, Benedíkt G. Ófeigsson, Erik Sturkell, Ásta Rut Hjartardóttir, Ronni Grapenthin, Halldór Geirsson, Elisa Trasatti, Sara Barsotti, Rikke Pedersen, Páll Einarsson, Bergrún Arna Óladóttir, Hildur Friðriksdóttir
Abstract
Abstract Unrest began in July 2021 at Askja volcano in the Northern Volcanic Zone (NVZ) of Iceland. Its most recent eruption, in 1961, was predominantly effusive and produced ∼0.1 km 3 lava field. The last plinian eruption at Askja occurred in 1875. Geodetic measurements between 1983 and 2021 detail subsidence of Askja, decaying in an exponential manner. At the end of July 2021, inflation was detected at Askja volcano, from GNSS observations and Sentinel‐1 interferograms. The inflationary episode can be divided into two periods from the onset of inflation until September 2023. An initial period until 20 September 2021 when geodetic models suggest transfer of magma (or magmatic fluids) from within the shallowest part of the magmatic system (comprising an inflating and deflating source), potentially involving silicic magma. A following period when one source of pressure increase at shallow depth can explain the observations.