Iceland Mag

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Iceland Mag

Geology

Two of the volcanoes of Vatnajökull continue to tremble, sharp quake in Bárðarbunga

By Staff

  • Volcanoes showing growing signs of activity All major volcanoes of South Iceland have been trembling in recent months. Photo/Loftmyndir.is

Two of the most powerful volcanoes of Iceland, Bárðarbunga and Öræfajökull have continued to show elevated levels of activity in the past couple of weeks. Bárðarbunga trembled on Sunday when a sharp 3.2 magnitude quake was detected in the eastern edge of the caldera. A swarm of few dozen smaller and deep quakes have been detected in Öræfajökull over the weekend.

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

In recent months all major volcanoes of Iceland have been showing significant and growing levels of activity. Geologists have determined that lava chambers of these major volcanoes and volcanic systems are quickly filling as magma is thrust up from the earth's core into the crust. In addition to Öræfajökull and Bárðarbunga the third major volcanic system of Vatnajökull, Grímsvötn has been showing signs of activity. Katla, beneath Mýrdalsjökull glacier and Hekla in South Iceland have been showing signs of activity.

Read more: Scientists determine sub-glacial volcano Bárðarbunga is showing increased geothermal activity

Bárðarbunga quake
The Icelandic Meteorological Office detected a 3.2 magnitude quake at a depth of 6.8 km, 7.2 km east-southeast of the center of Bárðarbunga caldera just before half past five on Sunday morning. The quake was followed by several smaller tremors.

Seismologists with the IMO told the National Broadcasting Service that the quake was clearly a continuation of the activity in recent weeks, and that there were no signs of immediate volcanic activity in the caldera.

Bárðarbunga is one of the most active and powerful volcanoes in Iceland. The volcano has been showing growing signs of activity since the end of the Holuhraun eruption, its last eruption in 2014-15. This eruption produced Holuhraun lava field in the central highlands, the largest lava field produced in Iceland since the 18th century. The growing activity in recent months is believed to be caused by the volcano's lava chambers being re-filled with magma.

Activity in Öræfajökull
Öræfajökull volcano in the southern part of Vatnajökull also trembled over the weekend, with more than 40 quakes having been detected since Saturday. 

Read more: Uncertainty phase still in effect for Öræfajökull volcano

Aerial photographs of the ice cap of Öræfajökull, published in the local newspaper Morgunblaðið, show that the recent spike in geothermal activity in the volcano's caldera has now melted a hole through the ice in one of the cauldrons which have formed in the ice in recent weeks. The geothermal activity can only be caused by magma which has been thrust close to the surface in the caldera. 

Activity in Askja
Significant levels of activity have also been noted around the crater lake Askja north of Vatnajökull, with swarms of relatively small and deep quakes in the past week. Askja is a very active volcano, located north of the Bárðarbunga system. The crater lake in Askja was formed in a 1875 eruption, but the last time the volcano erupted was in 1961.

A Páll Einarsson a professor of geophysics at the University of Iceland told the local TV station Stöð 2 that it was too early to say Askja was waking up. The seismic activity was more likely caused by magma being thrust into fissures in the crust, caused by the drifting apart of the continental plates. Páll pointed out that the activity in Askja was proof that significant magma movements were constantly taking place beneath the ground in Iceland, without these movements leading to an eruption.

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