Emerging Ice Cauldrons Near Grímsfjall Signal Recent Glacial Activity
Updated: 23 January at 9:00 UTC
In the days following the peak of the recent glacial flood in the Gígjukvísl river, water levels have begun to drop, returning to pre-flood conditions. The seismic activity recorded at Grímsfjall has also calmed, with tremors now back to standard levels. Over the past week, 21 earthquakes have been detected in Grímsvötn, with two registering above a magnitude of two.
During a similar flood in 2021, an ice cauldron (designated GV-33) took shape south of Grímsfjall—an area drained by the floodwaters beneath the glacier. Last week, a team from the Icelandic Meteorological Office, conducting measurements at Vatnajökull, discovered a depression that resembles the earlier cauldron. Analysis of satellite imagery from January 21 reveals two ice cauldrons in this region. One matches the cauldron from the 2021 flood, while the second may either be a new formation from the recent surge or an older one resurfacing. Travelers in the vicinity of Grímsfjall are advised to stay clear of these cauldrons.
Coordinates for the observed cauldrons:
- Cauldron GV-33: 64°23.611′, -17°13.017′ (decimal degrees, WGS-84)
- New cauldron: 64°23.766′, -17°12.729′ (decimal degrees, WGS-84)
As the glacial flood unfolded, the aviation color code for Grímsvötn was raised to yellow, indicating a heightened risk of volcanic activity due to shifting pressures beneath the glacier. With the flood now receding and no significant short-term seismic changes, this alert will be downgraded back to green.
Long-term observation of seismic patterns at Grímsvötn shows that the recent months have seen above-average earthquake activity. Should an eruption occur, it would likely be preceded by an uptick in seismic disturbances, albeit with potentially short warning times. Experts from both the Icelandic Meteorological Office and the Institute of Earth Sciences will continue their close watch on Grímsvötn and keep the public informed of any developments.
Updated: 15 January at 18:00 UTC
The water level in Gígjukvísl has stabilized since the previous evening, indicating that the river has reached its peak flow. The discharge is expected to gradually decrease in the upcoming days. Notably, since midnight on January 15, increased tremors recorded at Grímsfjall suggest heightened geothermal activity—an end-of-flood phenomenon that has been observed in past glacial outburst floods. While today’s seismic activity remains minimal, measuring below magnitude 2.0, a significant escalation might herald a potential eruption.
Updated: 15 January at 16:00 UTC
Seismic tremors indicating a glacial flood peaked late Saturday evening, with discharge rates stabilizing by Sunday. This trend aligns with prior jökulhlaup events, suggesting a similar pattern may unfold. Monitoring will continue as we assess the situation.
Updated: 12 January at 10:30 UTC
In recent days, Gígjukvísl has seen a notable rise in water levels, with the gauge at Highway 1 recording an increase of approximately 70 cm. Conductivity readings have also risen, confirming the influx of floodwater. Notably, no earthquake activity was detected along the flood path up to yesterday. Seismic data indicates that the outflow from Grímsvötn continues to increase, with expectations that the glacial flood will peak over the weekend.
Picture 1: Recent data from the Gígjukvísl water level gauge, illustrating the last week’s changes.
Picture 2: Average seismic amplitude readings at Grímsfjall over the past ten days, highlighting the uptick in tremors correlated to the ongoing flood.
The Icelandic Meteorological Office, in partnership with the Institute of Earth Sciences, will continue to monitor Grímsvötn closely. We will provide updates as necessary, with the next scheduled report expected on January 15, unless significant changes arise over the weekend.
For more information on Grímsvötn, please consult the Catalog of Icelandic Volcanoes.
Released: 11 January at 13:30 UTC
A magnitude 4.3 earthquake struck Grímsvötn at 06:53 this morning—its largest signal since monitoring began in 1991. The tremor was followed by a surge in Gígjukvísl’s water levels, indicating the onset of a glacial lake outburst flood. The earthquake likely reflects a release of pressure related to this flood. Communication with the GPS device on the ice shelf has been disrupted, complicating further evaluations.
This latest flood event follows previous instances in October 2022 and late 2021. Present estimates put the water volume in Grímsvötn at approximately 0.29 km³. While this volume is substantially greater than the start of the 2022 flood, it remains below that of the 2021 event. Thus, it is anticipated that the impacts of this flood will be minimal on infrastructure.
Historically, volcanic activity at Grímsvötn has occurred post-jökulhlaups, with eruptions typically triggered by the significant drop in water pressure. Although such events happened in 2004, 1934, and 1922, it’s worth noting that most floods have not resulted in eruptions.
As a precaution, the aviation color code for Grímsvötn was altered to yellow, reflecting its current state beyond normal activity levels.
The map below illustrates the flood’s path from Grímsvötn to Skeiðarársandur.
These images—a webcam capture from the bridge over Gígjukvísl—highlight water level variances observed between January 9 and 11.
The Icelandic Meteorological Office, along with scientists from the University of Iceland’s Institute of Earth Sciences, will keep a vigilant watch over Grímsvötn and relay further developments as they arise.