Bárðarbunga Eruption More Likely than Previously Thought

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Bárðarbunga Eruption More Likely than Previously Thought

Eyjafjallajökull eruption 2010

From the Eyjafjallajökull subglacial eruption in 2010. Photo: Jóhannes Benediktsson.

Scientists from the Icelandic Met Office and the Institute of Earth Sciences and representatives of the Civil Protection in Iceland met this morning for a meeting of the Scientific Advisory Board of the Icelandic Civil Protection. Among their conclusions is that an eruption in Bárðarbunga volcano is more likely than before. The eruption could cause an outburst flood and possibly an explosive, ash-producing activity. In the event of a subglacial eruption, it is most likely that flooding would affect the river Jökulsá á Fjöllum. However it is not possible to exclude the following flood paths: Skjálfandafljót, Kaldakvísl, Skaftá and Grímsvötn.

Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection in their meeting on Saturday morning, August 30:

  • "Earthquake activity continues on a 15-km-long region of the dyke intrusion, extending both into the Dyngjujökull glacier and the region north of the ice margin. Earthquakes have not migrated northwards during the last two days. Seismicity remains high and, since midnight, about 700 earthquakes have been detected in the region.
     
  • The largest earthquakes since midnight include: (i) a magnitude 4.5 event on the northern side of the Bárðarbunga caldera at 02:35 UTC; (ii) a magnitude 4.2 earthquake in the same region at 06:18 UTC; and (iii) a magnitude 5.4 earthquake on the south-eastern edge of the Bárðarbunga caldera at 07:03 UTC. During the last two weeks, several earthquakes of similar size have occurred on the edge of the Bárðarbunga caldera. These earthquakes are interpreted as signs of stress changes in the region of the caldera.
     
  • Over 20 micro-earthquakes have been detected in the Askja region. It is thought that these earthquakes have occurred due to stress changes north of the dyke intrusion.
     
  • GPS measurements show continued horizontal movements north of Vatnajökull due to formation of the dyke intrusion on the northern edge of the ice-cap.
     
  • No unusual changes in the discharge or electrical conductivity of Jökulsá á Fjöllum have been detected. The same applies to other rivers draining from north-western Vatnajökull.
     
  • A sample of newly erupted lava was taken from Holuhraun yesterday; analysis is ongoing.
     
  • There are no indications that the intensity of the activity declining.

At this moment it is unclear how the situation will develop. However, four scenarios are considered most likely:

  1. The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.
     
  2. The dike could reach the Earth's surface north of Dyngjujökull causing another eruption, possibly on a new fissure. Such an eruption could include lava flow and (or) explosive activity.
     
  3. The intrusion reaches the surface and an eruption occurs again where either the fissure is partly or entirely beneath Dyngjujökull. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
     
  4. An eruption in Bárðarbunga. The eruption could cause an outburst flood and possibly an explosive, ash-producing activity. In the event of a subglacial eruption, it is most likely that flooding would affect Jökulsá á Fjöllum. However it is not possible to exclude the following flood paths: Skjálfandafljót, Kaldakvísl, Skaftá and Grímsvötn.

Other scenarios cannot be excluded."

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