Grímsvötn, Iceland’s most active volcano, was placed under close surveillance by the authorities on Thursday due to a large glacial flood in progress, a possible prelude to an eruption.
Brutal natural phenomenon known as “ jökulhlaup », this tumultuous flow of water is underway near the volcano and flows along the immense sandur – an outwash plain formed by the melting of the ice caps – Skeiðarársandur, not far from Skaftafell in the south of the country , said the Icelandic Meteorological Institute.
The drop in pressure on the volcano caused by the flow of enormous quantities of water can trigger an eruption, as was the case in 2004, 1934 and 1922.
Currently, the volume of water is around 0.29 km3 and the maximum flow should not exceed 1000 m3/s, according to the Institute.
But glacial floods can also take place without an eruption – as in November 2021 and October 2022.
Located under the Vatnajökull glacier, the largest in Europe, in an inaccessible area of central Iceland, the Grímsvötn volcano – which is generally short-lived – last erupted in 2011.
Its ash cloud then briefly disrupted air traffic over the British Isles, far from the eruption of Eyjafjallajökull in 2010, which almost completely paralyzed traffic in Iceland and to Europe for days.
In recent months, the seismic activity of Grímsvötn has been above its usual levels, underlined the organization responsible for volcanic monitoring in a press release.
The latest volcanic eruption in Iceland, the fourth in two years, took place on the evening of December 18 in an area located south of the capital Reykjavik.
Grindavik, a small town of 4,000 inhabitants, was evacuated on November 11 as a precaution.
Thirty-three volcanic systems are considered active in this land of fire and ice, the most volcanic region in Europe.