There are indications that a glacial flood may have begun at Grímsvötn volcano under the Vatnajökull ice cap in Southeast Iceland, RÚV reports. Chief Superintendent of South Iceland police Oddur Árnason confirmed that police have been advised about the likeliness that a jökulhlaup is underway, but currently, the only solid data to confirm this is that GPS devices are registering changes in land elevation surrounding the volcano.
Finnur Pálsson, an engineer at the University of Iceland’s Earth Sciences Institute, oversees the measurements taken at Grímsvötn. Glacial meltwater collects in a subglacial lake and caldera in Grímsvötn’s core, both of which are covered by an ice cap. The water level of the lake rises slowly but surely, until finally, it overflows in a glacial flood. Finnur said that measurements showed the water levels under the volcano shifting by several centimetres yesterday but they’ve been stable ever since. In June, the water level of the subglacial lake was rising three centimetres a day in June, indicating that a flood could be imminent in coming weeks or months. Glacial floodwaters from Grímsvötn tend to run into the Gígjukvísl river and usually reach their apex within two to five days.
Finnur says that it’s currently uncertain whether there are some inaccuracies in the data, or if a glacial flood truly has begun. As such, the area will be closely monitored today and for the next 24 hours. If a glacial flood has begun, it would take a considerable amount of time for the floodwaters to reach settled areas.
At time of writing, the Icelandic Met Office was convening a meeting regarding the possible event and Civil Protection had also been in touch with local authorities. Police stations in the district have been informed, but no preparations had been undertaken yet.
Grímsvötn is the most active volcano in Iceland and has erupted as many as 100 times since the time of Iceland’s settlement, and 13 times since 1902. It is part of a volcanic system that is over 100 km long and extends down to the Laki craters. Grímsvötn last erupted in 2011—the volcano’s largest eruption in 140 years.
A glacial flood at Grímsvötn can trigger a volcanic eruption. Although these eruptions can be strong, the primary side effect has usually been disruptions to air traffic. If there is an eruption of Grímsvötn in coming days or weeks, scientists say it is unlikely to be as big as the one in 2011.