August 29, 2014

expert reaction to Bárðarbunga volcano in Iceland

Further reaction to activity in the Icelandic volcano.

Prof David Rothery, Professor of Planetary Geosciences at The Open University, said:

“The fissure eruption that began shortly after midnight in the Holuhraun region northeast of Bardarbunga is probably where the magma in the fissure that had propagated northwards (known as a dyke) over the past several days reached the surface.  Fissure eruptions begin as spectacular ‘curtains of fire’ composed of clods of molten basalt thrown tens or hundreds of metres into the air.  When they fall to the ground they can feed lava flows.  These events are not highly explosive and do not produce much fine ash. There is a small no fly zone in central Iceland, not affecting any Icelandic airports.

“If this eruption persists it could become a tourist attraction, as it will be relatively safe to approach, although the area is remote.  This event should not be seen as ‘relieving the pressure’ on Bardarbunga itself, nor is it a clear precursor sign of an impending Bardarbunga eruption.”

Prof Geoff Wadge, a volcanologist at the University of Reading, said:

“The activity beneath the Bardarbunga volcano in Iceland may have resulted in lava reaching the land surface below the icecap south of the volcano, but there is no current concern about ash disruption to air travel.

“Over the last few days the magma has been detected by seismometers moving northwards at a few kilometres per day. This could lead to a number of possible scenarios, based on experience of previous events in Iceland in the area around Bardarbunga. These scenarios involve the sideways movement, or intrusion, of magma in the crust away from the volcanic centre, sometime known as rifting.

“The magma could continue to move sideways, but might never reach the surface in an eruption. Alternatively, the magma could erupt at the surface intermittently through a series of fissures several kilometres long. This could go on and off for several years, as happened from 1975-1984 at Krafla volcano, considerably north of Bardarbunga. They would be relatively harmless, as this region is far from human inhabitation and would cause very little ash to be thrown into the atmosphere. These are the two scenarios which are the most likely to occur.

“However, it is also possible that the current path of the intrusion could take the magma northwards to the Askja volcano. There the presumed very fluid basaltic magma could interact with much stiffer rhyolitic magma, to produce a large explosive eruption, which is probably what happened to produce the major ash cloud of 1874. If it occurred again, it could be disruptive to European air traffic if the winds are coming from the north.

“Even less likely, but still possible, the eventual extrusion of lava could be at a very high rate, producing a flood basalt event, pouring lava out into the surrounding area. This happened at the Laki eruption of 1783-4 to the southwest of Bardarbunga, when a prodigious amount of gas was released that blighted the Iceland population and possibly created environmental effects in Europe, including an acid haze.”

Declared interests

None declared