Updates from Yesterday’s Long-Term Monitoring Meeting at IMO: Litli-Hrútur Eruption Declared Over, Uplift Detected in Torfajökull Volcanic System
Yesterday’s meeting on volcanic activity at the Icelandic Meteorological Office brought some clarity to three volcanic systems currently under observation. The eruption that captivated attention at Litli-Hrútur has officially come to an end. Meanwhile, uplifting activity has been recorded in the Torfajökull volcanic system, signaling potential changes beneath the Earth’s surface.
Recent deformation data reveals that inflation is ongoing at Askja, with its magma source remaining stable since September 2021. The magma, accumulating at approximately 3 kilometers deep, shows no signs of rising. Notably, the Torfajökull caldera has also experienced uplift, which began in June, with several centimeters measured from both InSAR and GPS data. The prevailing hypothesis suggests that magma is likewise accumulating below the surface in this area.
Figure caption: Satellite data (InSAR image) illustrating uplift in Askja from July 2021 to August 2023. The yellow and red areas highlight regions undergoing the most significant deformation.
Guidance for Visitors Remains Essential
Experts from the IMO are currently conducting measurements in Askja, with preliminary results expected by Thursday. The team is analyzing gas emissions and temperatures in both Lake Askja and the nearby Víti crater, as well as sampling to gauge the lakes’ pH levels. This data is crucial for monitoring any shifts in volcanic activity in accordance with a long-term observation plan for Askja.
Since the uplift began in September 2021, rangers and local guides have urged vigilance among visitors. Travelers are strongly advised to heed the instructions of rangers—guidance developed collaboratively with Iceland’s Civil Protection and local authorities. Bathing in Víti has been discouraged, and visitors should limit their time in the area. It’s worth noting that the level of uncertainty regarding Askja, as declared by Civil Protection, remains in effect.
A Look Back: The 1961 Askja Eruption
Reflecting on history, the last eruption at Askja commenced on October 26, 1961, and was characterized as an effusive eruption, consistent with most of the volcano’s past activity. Notably, a surge in geothermal activity preceded the eruption, with increased seismic events and new solfataras surfacing in the weeks leading up. The earthquake catalog from that time recorded six seismic events exceeding magnitude 3, with one surpassing magnitude 4.
Recently, the IMO received a report regarding a potential short-lived steam explosion near Bátshraun, just east of Víti. However, further investigation indicated that the observed plume was likely just dust blown by the wind. The area is known for small landslides and rockfalls, often accompanied by noise that echoes throughout the caldera. Given the recent dry conditions, fine particles are easily displaced by the wind.
Uplift Observed in the Torfajökull Volcanic Zone
As noted, measurements have confirmed uplift within the Torfajökull caldera, which began in June. This ongoing uplift, evident through several centimeters of movement detected via InSAR and GPS, suggests magma is also accumulating at depth here. Over the next few weeks, researchers will intensify their data analysis and model efforts to fine-tune understanding of the depth and volume of intruded magma. Importantly, no significant seismic changes are noted since the uplift began. The last eruption in Torfajökull occurred in 1477, and the volcanic system itself consists of a central volcano along with a fissure swarm extending 40 kilometers long and 30 kilometers wide. The caldera at the center measures approximately 18 by 12 kilometers and includes Iceland’s largest geothermal area, covering around 150 square kilometers.
Figure caption: Satellite data (InSAR image) displaying uplift in the Torfajökull caldera. Yellow and red areas indicate regions experiencing the most substantial deformation.
Figure caption: Map from the Icelandic Volcanoes Catalog illustrating the Torfajökull volcanic system.
Closure on the Eruption at Litli-Hrútur
It’s been ten days since any activity was recorded at the crater near Litli-Hrútur, and volcanic tremors have subsided to background levels. Current assessments show no deformation in the region, marking a significant reduction in seismic activity. As this chapter in the Reykjanes Peninsula’s volcanic narrative draws to a close, caution remains crucial. The newly formed lava retains considerable heat, with some areas still less solidified beneath a thin crust. Visitors should be wary of unstable lava edges, which may crumble and send larger fragments falling. Additionally, gas emissions from the lava can pool in lowered areas, posing a latent hazard. Fissures may also exist due to intense seismic activity preceding the eruption.