Earthquake swarm starts in the Bardarbunga caldera, Iceland


Icelandic Met Office (IMO) reports an earthquake swarm started in the Bardarbunga caldera at 02:15 UTC on September 7, 2017 when an earthquake of magnitude 4.1 occurred. The last eruption of this volcano started in September 2014 and ended in February 2015.

"Quite a few earthquakes have been detected, the largest one of magnitude 4.5 at 03:08 UTC. There is no volcanic tremor visible," IMO's specialist said.

A total of 36 earthquakes were registered between 02:15 and 17:48 UTC, with magnitudes ranging from 0.1 to 4.5 and depths between 0.8 and 7.1 km (0.5 and 4.4 miles).

There are currently no signs of increased volcanic activity in the area, although it has seen a large number of quakes over the past years.

Barbarbunga is located north-west of Vatnajokull, Iceland's largest glacier and is considered a highly active volcanic area.

Earthquake swarm Bardarbunga caldera September 7, 2017

Geological summary

The large central volcano of Bárðarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 cu km, have occurred throughout the Holocene into historical time from the Veidivötn fissure system.

The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system to the SW is also part of the Bárðarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárðarbunga potentially affect drainages in all directions. (GVP)

Featured image: Vatnajökull, also known as the Water Glacier. Credit: Anjali Kiggal

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