Update Fri 19 Sep 17:12No significant changes have occurred at the ongoing fissure eruption in Holuhraun. The lava effusion rate seems to remain stable, according to IMO.
Subsidence, or slow caldera collapse, of the Bárdarbunga caldera continues at rates of approx. 50 cm per day.
Seismic activity remains elevated. The largest earthquake yesterday and today was a magnitude 5.3 event at 14:21 local time and a magnitude 4.7 this morning.
Irregular horizontal displacements of the crust revealed by GPS stations probably indicate that magma movements underground are changing, but it is impossible to predict what the consequences will be.
Scientists concluded from chemical analysis and modelling that the magma currently erupted has been coming from a storage area below 10 km depth. This is another indicator that the eruption could be a long one, as the reservoir that has been feeding it is likely to be a large one.
Eruption continues with little changes
Update Thu 18 Sep 21:32IMO reports that the eruption continues at similar intensity as during the past days. Fog prevented visual observations at the fissure eruption today.
The Bárdarbunga volcano's caldera continues to sink at a rate of approx. 50 cm per day. Earthquakes continue to occur at the northern caldera rim and - lesser and much smaller, below magnitude 2 - along the northern part of the dyke, mostly under the Dyngjujökull glacier.
The largest quake had a magnitude 5.3 at the northern rim of Bárðarbunga caldera at 14:22. This quake was associated with a drop of 15 - 20 cm of the caldera floor.
Continuing fissure eruption, caldera subsidence, seismic unrest and sulphuric gas emission
Update Thu 18 Sep 17:38Both the fissure eruption at Holuhraun and subsidence of the Bardarbunga caldera continue at similar rates as yesterday.
Seismic activity has however been rather intensive today with already 7 earthquakes larger than M 3.0 detected so far since midnight (local time) - the biggest of which was as strong as M 5.2 and occurred at 14h21 UTC. Smaller earthquakes also continue to shake up the ground along the Bardabunga caldera and the subsurface dike intrusion. GPS monitoring of the last few days shows irregularity in the crustal movements which could be a sign for a change in the magma movement under Bardarbunga.
The Icelandic Met Office considers the following two scenarios to be most likely:
-The eruption on Holuhraun declines gradually and subsidence of the Bardarbunga caldera stops.
- Large-scale subsidence of the Bardarbunga caldera occurs and results in either an eruption at the edge of the caldera or southwards lengthening of the now active Holuhraun eruptive fissure. Both scenarios would place active vents directly beneath the glacier and lead to significant melt water floods and the production of volcanic ash.
For now, however, the main warnings involve the migration of volcanic gasses rich in sulphuric acids from the eruption site towards the northern parts of Iceland. The Icelandic Met Office offers continuously updated maps of the prediction of such gas pollution and advises people that detect these gasses to stay indoors, close the windows, turn up the heat and switch of the air conditioning.
The main vent with 100-200m tall lava fountains feeding the large river of glowing hot lava. Photograph taken by Tom Pfeiffer on the 13th of September.
eruption and deformation of volcano's caldera continue
Update Wed 17 Sep 16:47The eruption at Holuhraun continues. According to the Icelandic Met Office, there are no signs of decreasing magma output. The lava flow field continues to spread.
At the Bárdarbunga caldera, subsidence of 50 cm / day continues. GPS measurements show irregular deformation patterns, but it is not completely clear what these mean except that the magma movements underground are probably changing their paths.
Seismic activity today and yesterday has been rather intensive, IMO wrote in its latest update:
"Yesterday 7 earthquakes larger then M3,0 were detected in Bardarbunga. The biggest were M5,4 and M4,8 last night. Smaller earthquakes were detected in Dyngjujokull glacier and in north part of the dyke."
Fissure eruption decreases, but seismic activity continues
Update Tue 16 Sep 16:25
The lava flow field at Holurhaun on 13 Sep
Eruptive activity at the Holuhraun fissure is decreasing and many believe that it might end within some days. This does not necessarily mean that the eruption & crisis is over, however, but could be just a pause.
Lava fountain from Holuhraun on 13 Sep
We have posted sets of photos from our recent visit during 12-13 Sep.
Seismic activity continues at reduced rate, with a few 100 events detected daily, mainly below magnitude 3. Most of them have now been under the Bárðarbunga volcano caldera and the ring fault that has formed there, producing subsidence at a rate of approx. 50 cm per day. This process has been referred to as a slow caldera formation.
It has been one month since the seismic crisis at Bárðarbunga volcano started. So far, around 20.000 earthquakes have occurred since a month ago - compared to Iceland's normal yearly average of 12,000 earthquakes. More than 200 quakes had magnitudes larger than 3.
It is expected that the current rift episode continues in pulses for possibly months to even years. New fissures could open up, in particular once the Holuhraun fissure closes down and allows for pressure build-up. The risk of a subglacial eruption and associated floods and ash emissions remains high.
Pollution by SO2 in downwind areas in eastern Iceland has become a serious problem.