The image shows the near-vertical deformation in mm for the period 1-21 August. The InSAR image is obtained from two passages of Sentinel-1 satellite. (Click the image to read more)

Uplift signal detected in Askja volcano


GPS observations and ground deformation maps derived from Sentinel-1 satellite data reveal that Askja volcano began inflating at the beginning of August 2021. The uplift signal is centered on the western edge of Öskjuvatn, close to Ólafsgígar, and corresponds to ~5 cm/month of vertical motion. Geodetic modelling (performed using both GPS and satellite data) indicates that the source of this inflation is located at a depth of approximately 3 km and corresponds to a volume change of approximately 0.001 km³/month.

The cause of such inflation is uncertain, but most likely it is due to the inflow of new magma. Askja volcano is seismically active and earthquakes are regularly measured in the area. 

The last eruption at Askja was in 1961. Regular geodetic measurements were done in 1970-1972 and showed a period of uplift, however no further measurements were acquired until 1983. Since then, a continued subsidence of a rate of 1 cm/year was detected until this current inflation phase started. 

Active volcanoes in Iceland are often characterized by periods of inactivity, lasting years to decades, with intervals of enhanced seismicity, geothermal activity, and inflation. In most cases, magmatic intrusions do not culminate into an eruption. At this stage it is then very difficult to anticipate how the situation will evolve. The inflation is continuing at present (3. Sept 2021) and will be closely monitored by IMO which will distribute additional information in case of further changes. 

More information about Askja volcano is available at 

Data from the GPS station OLAC (location shown in the InSAR image), for the North, East and Up components over the period 27 July – 2 September 2021. The station, which is located close to the center of the inflating area, shows that the uplift started between the end of July and beginning of August (mainly visible in the Up component) and it is still ongoing (2. Sept 2021). The dashed red line indicates the rise speed that is assessed to be ~5 cm /month.

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