Our colleague Gísli Pálsson wrote this morning from Iceland, “The show is on; this time a considerable eruption.”
At the Holuhraun lava field, lava has been erupting since Sunday morning. These lava fountains reach more than 50 meters high. Though they are dramatic, they do not release ash that would interfere with aviation. This activity is about five kilometers from Dyngjujökull Glacier. If the fissure opens under the glacier, floods might result.
These lava fountains are just part of the activity along the fissure that stretches to the northeast from Bárðarbunga. As the attached map shows, there have been a large number of earthquakes in recent days associated with this fissure, though there is earthquake activity nearby as well, linked to other fissures and faults. This map comes from a source tweeted out by Dave McGarvie, a remarkably well-informed volcanologist who is currently in Iceland. For more information, you can follow an animation of the earthquake activity, also tweeted by McGarvie.
At the northeast end of the fissure, directly at Bárðarbunga, the risk of a subglacial eruption has increased. The earthquake activity continues to be strong, with one earthquake today registering 5.1. A flight over the glacier on Friday noted new crevasses, a sign of melting at the base of the glacier. As a result, the risk to aviation has been raised again to red, for the third time. A small portion of the airspace north of the area has been closed to aviation, but no airports or commercial flights have yet been affected. The evacuation orders continue in effect.
Further reconnaissance will have to wait a day or two. The remnants of Hurricane Cristobal are approaching Iceland, bringing winds of 40 to 50 miles per hour and rains. The heaviest rains are expected in the southeast of the country, around the area of the eruption. The storm will pass, but the future of the eruptions remains uncertain.
As the earthquakes continue at Bárðarbunga volcano, under Iceland’s largest glacier, local authorities and residents have become increasingly concerned about the risk of outburst floods, though the warning remains at code orange. They recognize that large quantities of water could rush down river valleys if magma should rise to the surface. As a precautionary measure, residents and tourists have been evacuated from two areas north of the glacier. Icelandic authorities have also prepared contingency plans in case floods threaten major hydroelectric facilities.
Another site reports that a number of farmers have rounded up their sheep and horses, who range freely to forage in the summer and early fall. The animals are confined indoors during the long Icelandic winters, where the farmers must supply them with fodder. The farmers and animals alike do not enjoy an early round-up, but the risk of losing animals to floods or to ash-clouds is too great to dismiss.
There have been many earthquakes in the last two days, since GlacierHub last reported on this situation. The first map below, from the Icelandic Meteorological Office, shows how the quakes are tightly clustered. The second, a visualization by Bæring Gunnar Steinþórsson, shows the quakes in three dimensions. His site, http://baering.github.io/, allows viewers to adjust the angle of view and the period that is covered.
As recent reports by Eric Holthaus in Slate and by Dave McGarvie in The Conversation have discussed, there are a variety of types of floods and explosive ash releases that could occur if lava were released at Bárðarbunga, under a layer of ice that is 400 meters thick. it is unlikely that an eruption would disrupt air traffic as seriously as the 2010 event at Eyjafjallajökull. Holthaus modeled a likely scenario of ash transport, should an eruption occur, which shows that it would pass over major airports, but mentions that fewer flights would probably be disrupted, thanks to better forecasts and more effective regulations.
Nonetheless, as the Icelandic anthropologist Ásdís Jónsdóttir wrote in a recent email, “We have to keep in mind that there have indeed been regular eruptions… in the past.” The twelve hundred years of Iceland’s recorded history and the geological evidence from before that demonstrate the great power of Iceland’s volcanoes and glaciers. For the time being the surface of Bárðarbunga remains calm, as shown by these photos that Jónsdóttir took on a recent trip.