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Iceland Mag


Bárðarbunga, the other monster volcano of Vatnajökull trembles: Two sharp 3.9 magnitude quakes

By Staff

  • Growing activity Steam rising from ice cauldrons in the Bárðarbunga caldera. A recent spike in geothermal activity in the volcano has managed to melt a hole through the glacier's ice cap. Photo/Jóhann K. Jóhansson

Two sharp 3.9 magnitude earthquakes were detected in Bárðarbunga volcano shortly before two in the afternoon. The two quakes have been followed by a few smaller quakes. The first quake hit at 13:53, followed by a second quake two minutes later. The volcano has been showing signs of growing activity in recent weeks. A second giant volcano in Vatnajökull glacier, Öræfajökull has also been showing signs of growing activity.

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

Quakes 21.11.17

Quakes 21.Nov 2017 The two powerful quakes are marked with green stars. Photo/IMO

The Seismic Monitoring System of the the Icelandic Meteorological Office detected the first quake 8.0 km (5 mi) north-northeast of the center of the volcano's caldera at a depth of 4.6 km (2.9 mi). The second quake had an epicenter in 6.1 km (3.8 mi) northeast of the caldera center at a depth of 3.9 km (2.4 mi). 

Any quake in an active volcano which is larger than three on the Richter scale is considered a powerful quake. Quakes larger than 4 are relatively rare, and are associated with significant geological activity in the volcano.

Earlier this month scientists discovered a significant increase in geothermal activity in the volcano. Aerial reconnaissance of the volcano revealed that the geothermal activity has melted a hole in the glacier ice cap. Steam plumes can now be seen rising from the ice cauldrons created by this activity. 

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

At the end of October the volcano was hit by the most powerful quakes since the end of the 2015 Holuhraun eruption. The eruption produced the largest lava field in Iceland since the 18th century. 

Growing signs of activity

volcanoes of Vatnajökull - Bárðarbunga

Volcanoes of Vatnajökull Bárðarbunga, Grímsvötn and Öræfajökull. Photo/Vísir, Garðar

Bárðarbunga is not the only Icelandic monster volcanoes showing worrying signs of growing activity. Öræfajökull, which is located in the southern part of Vatnajökull, has been stirring in recent years. These two are considered to be among the most powerful in Europe, if not the world. Öræfajökull is responsible for the second deadliest eruption in Icelandic history.

No signs of imminent eruption
Seismologists at the Icelandic Meteorological Office stress that there are no signs of imminent volcanic activity. The giant sub-glacial volcano has been very active since the end of the Holuhraun eruption, showing signs of significant activity in recent weeks. 

The third major volcano of Vatnajökull, Grímsvötn in the central part of the glacier, has not shown signs of growing activity.

Read more: Uncertainty phase still in effect for Öræfajökull volcano

The quakes in Bárðarbunga are caused by the re-filling of the volcano's magma chambers which were emptied in the 2014-15 Holuhraun eruption. As magma is thrust from the earth's mantle up into the crust the earth trembles.

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