Iceland Mag

11 Reykjavik

Iceland Mag

Geology

Glacial outburst flood from Vatnajökull largest on record, no serious damage to infrastructure

By Staff

  • The flood The scene in Skaftárdalur valley in SE Iceland. Photo/Benedikt Ófeigsson, IMO

  • The Ring Road Shortly after this photo was taken the Ring Road west of Kirkjubæjarklausutr village was closed to traffic. Photo/Einar Árnason

  • The Ring Road The road is built to withstand regular outburst floods. The road withstood this onslaught. Photo/Ágúst Freyr Bjartmarsson

  • One of two Skáftárketill cauldrons As the water is released the ice above subsides, creating large cauldrons in the ice cap of Vatnajökull. Photo/Þorsteinn Þorsteinsson IMO

The glacial outburst flood from Vatnajökull which began on Friday is the largest on record, measurements by the Icelandic Meteorological Office reveal. The flood is quickly receding after having peaked on Saturday.

Traffic along the Ring Road in South East Iceland was affected by the flood, as the water submerged the Ring Road west of the village Kirkjubæjarklaustur. Despite this it appears the flood has not caused any serious damage to infrastructure. Most importantly the Ring Road in South East Iceland withstood the flood. 

Glacial outburst floods - "hlaup"
Glacial outburst floods take place when meltwater from the glacier bursts out in a sudden flood. These floods can be caused either by the sudden melting of the ice in a volcanic eruption, or by the sudden release of meltwater which has been trapped beneath the glacial ice. Geothermal activity in volcanoes or geothermal areas located beneath the ice cap of glaciers melts the ice. The meltwater can either find its way to the nearest river, or it can collect in subglacial valleys or volcanic craters, where it's held in place by the sheer weight of the glacier ice above. When the water pressure rises sufficiently it can lift the glacier, releasing the water in a violent outburst flood. These events are called glacial outburst floods, or hlaup.

Grímsvötn geothermal area and volcano in the western part of Vatnajökull produce regular glacial outburst floods. These floods, called Skaftárhlaup take place once ever 2-3 years. The intensity of the floods depends on numerous factors, including the level of geothermal activity in Grímsvötn. 

The IMO estimates that the flood delivered 500 gigaliters (500 billion liters/132 billion gallons) of water to the ocean. The volume of the rivers delivering the outburst flood from the glacier increased more than sixfold during the flood. The second largest Skaftárhlaup outburst flood was in 2015, 425 gigaliters. 

Related content

Editor's Picks