Ongoing magma accumulation observed at Askja volcano despite slowed land uplift, Iceland
Image credit: Michelle M. Parks/Væðurstofa Íslands
Askja volcano in Iceland remains under close watch as scientists record a 12 cm (4.7 inches) uplift over the past year. The ongoing monitoring efforts have identified significant magma accumulation at a depth of 3 km (1.9 miles), yet there is no immediate threat of eruption. The last eruption at this volcano took place in 1961 (VEI 2).
A field trip to Askja was conducted by the Icelandic Meteorological Office, the Institute of Geosciences at the University of Iceland, and the University of Gothenburg in August 2024. The trip involved geodetic, pH, temperature, and gas measurements to monitor the area’s volcanic activity.
Data from the trip indicate that the land uplift in Askja continues, although the rate has slowed since September 2023. The GNSS station OLAC, located west of Öskjuvatn, recorded a 12 cm (4.7 inches) land rise over the past year and satellite data from InSAR and tilt measurements corroborate this ongoing uplift.
Modeling calculations suggest that magma accumulation in the area is occurring at a depth of about 3 km (1.9 miles), with no indications that magma is moving closer to the surface. Approximately 4.4 million m3 (155.4 million feet3) of magma have accumulated in the past 12 months, bringing the total volume change since July 2021 to about 44 million m3 (1.6 billion feet3).
Measurements taken in Víti crater showed no significant changes in pH, water temperature, or chemistry. The area continues to be closely monitored, especially since uplift was first detected in the summer of 2021, leading to increased monitoring efforts.
Historical data show that the first deformation measurements in Öskja began in 1966, with significant uplift observed between 1970 and 1972. The land then subsided until 2021, when uplift was once again detected. The previous uplift occurred without subsequent eruptions.
The last eruption in Askja was in 1961, resulting in the formation of the Vikrahraun lava field during an alkaline lava eruption. This type of eruption is common in the area, with similar events occurring in the early 20th century. In 1961, increased seismic and geothermal activity was noted 20 days before the eruption, with six earthquakes of magnitude 3 or higher recorded.
Acidic explosive eruptions have occurred in Askja, the most recent on January 3, 1875. It resulted in the formation of a smaller 4.5 km (2.8 miles) wide caldera, now filled by Öskjuvatn Lake, that truncates the rim of the larger central caldera.
Prior to that eruption, increased geothermal activity and frequent earthquakes were reported. However, based on historical patterns, similar large-scale events are considered unlikely in the near future.
If an eruption does occur, it is expected to be relatively small, similar to those in the 20th century, i.e. relatively small lava eruptions with minor pyroclastic fall. If it happens beneath Öskjuvatn, it could lead to an explosive eruption while the magma is isolating itself from the water.
References:
1 Annual measurements were made in Askja in August – IMO -September 2, 2024
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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