Iceland Mag

8 Reykjavik

Iceland Mag

Nature

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

By Staff

  • The four volcanoes Three of the most active and powerful volcanoes are located beneath thick ice sheets, while Hekla is a solidary cone volcano. Photo/Loftmyndir.

Growing seismic activity in the major volcanic systems of Iceland has put scientists and civil protection authorities on alert. While there are no signs of immediate eruption in any of the major volcanic systems, growing seismic activity, growing geothermal activity and the expansion of the crust in these systems indicates they are all in an unusually active phase.

Iceland has at least 30 active volcanic systems, all of which are under constant observation by scientists. The four most active volcanoes and volcanic systems in Iceland are Bárðarbunga and Grímsvötn both of which are located beneath Vatnajökull glacier, Katla, which is hidden under Mýrdalsjökull glacier and the cone volcano Hekla in South Iceland. Each has shown signs of growing activity in the past few months a geophysicist Páll Einarsson told the local newspaper Fréttablaðið.

Growing unrest in Katla

Katla, Mýrdalsjökull

Katla The Katla caldera is located beneath Mýrdalsjökull glacier. It is 30 km (18.6 miles) across and covered with a 700 m (0.4 mile) thick ice cap. Photo/Vilhelm

The volcano Katla has been particularly active in the past few months. Several large earthquakes have taken place in the caldera since last fall, the latest a 4.3 magnitude earthquake last Thursday. “Katla is more active during some years, and some years she is less active. This past year, since last fall, has been one of the more active years, even if it has yet to set any records.”

Read more: Eruption in giant volcano Katla grows more likely. Tourism poses challenges for evacuation

Last week the Department of Civil Protection and Emergency Management board of scientists said that the growing activity raised concerns and recommended increased monitoring of Katla. Historically Katla has erupted very regularly with 60-80 years between eruptions, on average. The last eruption took place in 1918, making Katla long overdue for an eruption.

Hekla gearing up for an eruption
One of the most active volcanoes in Iceland, Hekla in South Iceland, is also overdue for an eruption. The cone volcano has erupted on average every ten years. The last eruption took place in 2000. Measurements showed that the magma chambers of Hekla were quickly filling up this past summer, indicating the mountain was ready to blow any time.

Páll told Fréttablaðið that Hekla did not show immediate signs of eruption, but added that eruptions in Hekla tend to begin without any warning. However, all measurements show growing pressures building up in the magma chambers of Hekla.

The volcanoes of Vatnajökull

Grímsvötn 2011 eruption

Grímsvötn The ash plume rising from the 2011 eruption Photo/Egill Aðalsteinsson

Both of the large volcanoes beneath Vatnajökull have shown increasing activity in the past months. Powerful earthquakes in Bárðarbunga, the largest and most powerful volcanic system in Iceland, indicate the magma chambers beneath the main caldera are quickly filling up after the 2014-15 Holuhraun eruption.

The latest major seismic episode in Bárðarbunga took place on Monday when a 4.3 and 4.0 magnitude quakes hit the eastern part of the main caldera.

Read more: Powerful earthquake swarm in Bárðarbunga volcano: 4.3 and 4.0 magnitude quakes

History suggests that volcanic activity in the Bárðarbunga system comes in drawn out episodes, each lasting several years. If this holds up the 2014-15 Holuhraun eruption will likely be followed by further eruptions.

The fourth major volcano showing growing activity is Grímsvötn, located beneath Vatnajökull, to the south of Bárðarbunga. Eruptions in Grímsvötn are quite common. The Grímsvötn volcano has erupted on average once every seven years in the past. The last eruptions took place in 1998, 2004 and 2011. Páll told Fréttablaðið that the volcano was showing growing seismic activity. “Growing seismic activity points to an eruption in the next few years.”

Varying levels of danger
Of the three volcanoes eruptions in Bárðarbunga and Katla are most likely to pose significant risks to people. An eruption in Katla would create glacial outburst floods which threaten areas where large numbers of people can be expected to be located at any time, including the village of Vík in south Iceland, but also on the black sand beaches of Sólheimasandur where the wreck of a DC-3 airplane draws large numbers of visitors every day.

Eruptions in Katla and Bárðarbunga could also create massive ash plumes which could pose danger to air traffic.
 

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