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Iceland Mag

Geology

Scientists monitor spike in geothermal or volcanic activity beneath Vatnajökull glacier

By Staff

  • Bárðarbunga The giant volcano, one of the largest volcanic systems in Iceland, is hidden beneath Vatnajökull glacier. Photo/Magnús Tumi.

Travellers are being urged to stay away from the source of Jökulsá á Fjöllum at the northern edge of Vatnajökull glacier, as scientists attempt to determine the cause of a small glacial flood in the river. According to a statement from the Icelandic Meteorological Office electrical conductivity in Jökulsá á Fjöllum, one of the glacial rivers carrying melt water from the northern edges of Vatnajökull glacier has been growing in recent weeks. The river has also turned an unusually deep red. A strong smell of sulfur emanates from the river. 

Possible signs of volcanic activity
All of these are signs of geothermal and/or volcanic activity. Conductivity in Jökulsá á Fjöllum at two measuring stations is now double the normal. Higher conductivity could be caused by a spike in geothermal activity beneath the glacier, which in turn could be caused by growing volcanic activity, or by the sudden emptying of geothermal water which has built up beneath the glacier.

Read more: All of Iceland‘s major volcanoes showing unusually high levels of activity

Geothermal areas beneath the glacier melt the ice, building up large sub-glacial lakes. When the pressure of meltwater becomes large enough, it lifts the glacier, allowing the water to escape. Such glacial floods occur regularly, and usually follow a relatively predictable pattern. Scientists therefore monitor these floods closely for signs of changes in the geological activity beneath the glacier. The current activity in Jökulsá á Fjöllum does not fit a known pattern.

Glacial outburst flood and "hidden" eruptions
Scientists have so far been unable to determine the origin of the meltwater which has had this effect on Jökulsá á Fjöllum. Seismic measurements have not shown anything unusual, and there are no signs of growing volcanic activity. 

Read more: See the first photos from inside the burnt out Holuhraun crater

But as volcanologists who have spoken to local media point out, the absence of measurements does not rule out growing activity. Such glacial eruptions have taken place beneath Vatnajökull glacier without scientists noticing. Recent studies have shown that four previously unknown eruptions took place beneath Vatnajökull glacier since the 2014-15 Holurahun eruption.

Monster volcano Bárðarbunga a possible culprit
Two volcanic systems located beneath the North-Western part of Vatnajökull are believed to be the most likely sources: Bárðarbunga or Kverkfjöll. Bárðarbunga has been showing growing signs of activity since the end of the 2014-15 Holuhraun eruption. If the changes in Jökulsá á Fjöllum are caused by activity in Bárðarbunga it could be signs of "something more", according to a volcanologist who spoke to the local news site Vísir.

Read more: Quick primer on Bárðarbunga, Iceland's most powerful volcano

Scientists had planned to fly over the region this morning to get a better idea of what is happening beneath Vatnajökull, but had to cancel the research expedition due to bad weather.

We at Iceland Magazine are monitoring this story closely.

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