Bardarbunga volcano update: Fissure eruption decreases, but earthquakes pick up again - what's next?
Mi, 3. Sep 2014, 06:0506:05 AM | VON: T
View of the eruption this morning (Mila webcam)
Earthquakes near Vatnajökull during the past days (IMO)
Depth vs time of the recent earthquakes
Important changes seem to be under way. The fissure eruption with its spectacular lava emission at the surface still continues, but has decreased a lot since the first two days.
Satellite image of the eruption yesterday (NASA)
At the same time, earthquake and deformation activity that had decreased yesterday have picked up again. This is likely because the internal pressure is no longer efficiently released and intruding magma no longer erupted at the same rate as added underground.
The scenario of a new eruption along new fissures, possibly under the ice, or even at Bárdarbunga or Asjka volcanoes, is considered a possible scenario.
Small explosions were reported to have occurred in an area north of the glacier, but it is unclear what they were caused by. A possibility includes phreatic (purely steam-driven) or phreatomagmatic (magma directly in contact with water) explosions as magma (or surface lava flows) meets and heats up wet sediments.
As lava from the ongoing Holuhraun eruption continues to flow towards the nearby glacial river Jökulsá á Fjöllum, Iceland's second largest river from Vatnajökull, and only approx. 6 km away yesterday, the interaction of lava flows with the river water will likely generate powerful steam explosions that can release dangerous gases.
A magnitude 5.5 earthquake occurred at 03:09 this night at the northern caldera of Bárdarbunga. GPS data indicate that since the beginning of the crisis, the caldera is slowly subsiding as magma flows away from underneath. This increases the risk of an explosive eruption at the volcano itself.
Earthquakes along the dyke (magma intrusion at depth) NE of the volcano have continued in two clusters: one is in the area of the current eruption,along a 20-25 km long NNE-oriented stretch under the glacier edge, the latest eruptive fissure and north of it. The second cluster is NE of Askja to the north, suggesting that some of the intrusion has even progressed into Askja's volcanic zone.
Status as of yesterday
The eruptive fissure was 1.5 km in length, positioned about 4.5 km from the ice margin of Dyngjujökull. At 14:00 UTC yesterday, the lava flow was 4.2 km2 in area. At 08:00 UTC the edge had extended 1.5 km to the east-south-east.