Iceland Mag

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Iceland Mag

Geology

Largest earthquake swarm in Bárðarbunga since 2015 end of massive Holuhraun eruption

By Staff

  • The Holuhraun eruption The 2014-15 eruption from the Bárðarbunga system produced the largest lava field in Iceland since the 18th century. Photo/Institute of Earth Sciences.

Four powerful quakes were detected in Iceland's largest volcano around midnight. The first quake, a powerful 3.9 magnitude quake was detected at 23:02, followed by a second 3.2 magnitude quake only a minute later. At 23:26 and at 24:16 two 3.7 magnitude quakes were detected. These two quakes are the most powerful which have been detected in the volcano since the end of the 2015 Holuhraun eruption. The eruption produced the largest lava field in Iceland since the 18th century.

The powerful quakes were accompanied by half a dozen significant tremors, ranging from 1.3 to 2.8. 

Quakes in Bárðarbunga 27.10.17
Quakes in Vatnajökull in past 48 hours The quakes in Bárðarbunga are marked with a green star. Photo/IMO

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. 

No signs of imminent eruption
Seismologists at the Icelandic Meteorological Office told the National Broadcasting Service RÚV 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 latest swarm took place earlier this week.

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

The Seismic Monitoring System of the the Icelandic Meteorological Office detected the first 3.9 magnitude quake 5.9 km (3.7 mi) north-northeast of the center of the volcano's caldera at a depth of 4.1 km (2.5 mi). One minute later the second 3.2 magnitude quake had an epicenter in the same part of the caldera, but at a depth of only 100 m (330 ft). The epicenters of the powerful 4.7 magnitude quakes were also in the north-eastern part of the caldera, but at a greater depth, of 5 km (3.1 mi) and 3.1 km (1.9 mi).

Volcano is filling up its lava chambers 
The quakes are connected caused by magma being thrust from the earth's mantle up into the lava chambers of the volcano. The volcano has been re-filling it's lava chambers since the end of the 2014-15 Holuhraun eruption. 

Read more: Why the constant earthquakes? Iceland is slowly being torn apart

Bárðarbunga, which is one of the most powerful volcanic systems in Iceland, is hidden beneath the north-western part of the ice cap of Vatnajökull glacier. 

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