Tuesday, August 26, 2014

Icelandic Met Office: Bárðarbunga Update – Aug 26th




# 9001


Although no surface eruption has occurred, seismic activity under and nearby the glacier-covered Bárðarbunga caldera continues to escalate, with the largest event – an M5.7 quake – hitting last night. 


It is still highly uncertain what happens next, but given the history of this particular volcano, no one is ready to relax.


In today’s update the Icelandic Met Office presents three possible scenarios ranging from a gradual decrease in seismic activity, to a large scale fissure eruption. 


26th August 2014 11:50 - from the Advisory Board of scientists

Scientists from the Icelandic Met Office and the Institute of Earth Sciences, and representatives of the Civil Protection in Iceland, attend the meetings of the Advisory Board.

The following points were the conclusion at a meeting of the Advisory Board today:

  • Intense seismicity continues. Over 500 events have been recorded since midnight.
  • Seismicity continues to migrate northward. Seismicity is now concentrated on the 10 km long tip of the dike extending 5 km beyond the edge of the Dyngjujökull glacier.
  • At 01:26 this morning an earthquake of magnitude 5,7 was observed beneath the Bárðarbunga caldera.
  • The dyke beneath Dyngjujökull is now thought to be close to 40 km long. Modelling
    of GPS data indicates that about 50 million cubic meters of magma have added to the volume in the last 24 hours.
  • There are no indications that the intensity of the activity declining. The following three scenarios are still considered most likely:
    • The migration of magma could stop, accompanied by a gradual reduction in seismic activity.
    • The dike could reach the surface of the crust, starting an eruption. In this scenario, it is most likely that the eruption would be near the northern tip of the dyke. This would most likely produce an effusive lava eruption with limited explosive, ash-producing activity.
    • An alternate scenario would be the dyke reaching the surface where a significant part, or all, of the fissure is beneath the glacier. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
  • Other scenarios cannot be excluded. For example, an eruption inside the Bárðarbunga caldera is possible but presently considered to be less likely.
From the Icelandic Met Office:

The Aviation Color Code remains at the "orange" level.

26th August 2014 06:45 - from geoscientist on duty

Seismic activity continues to be high.

Biggest earthquake in the current swarm was measured this night at 01:26. According to USGS the magnitude was 5.7. The event was localized in the northern/northwestern part of Bardarbunga caldera at 6 km depth.

Most of the seismic activity is close to the rim of Dyngjujokull. The dyke is still migrating to the north and the tip of it is already around 10 km outside of the glacier. Most of the events are at the depth of 8-12 km.

There have been no signs of harmonic tremor.

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