Activity at Bárðarbunga: is Another Icelandic Volcano About to Erupt?

*UPDATE: Bárðarbunga Alert is now at orange level*

Few people, in northern and western Europe, at least, need a reminder of the chaos caused by the eruption of Iceland’s Eyjafjallajökull volcano in the spring of 2010, which closed airspace and disrupted travel for over a week.

Now, increasing levels of seismic activity at Iceland’s Bárðarbunga volcano have raised the spectre of a possible eruption. How likely is that to happen — and what might be the implications of another volcanic eruption?

Volcanism in Iceland

Iceland is highly volcanically active. The region is unique because magma reaches the surface from two sources – a deep mantle hotspot and a spreading ridge at the connection between two of the Earth’s tectonic plates.

The Smithsonian Institution’s Global Volcanism Program database lists 30 volcanic centres on the island, many with more than one possible eruptive source. On average, there is a noteworthy eruption approximately every five years.

The majority of the country’s eruptions are relatively small, and casualties few. According to Dugmore’s Black Sun, High Flame, and Flood: Volcanic Hazards in Iceland in 2012, “it is notable that despite over 200 volcanic events that could have led to a disaster, few have killed people either directly or indirectly.”

However, major eruptive events still have the possibility to cause widespread havoc — and have down so in the past. But increasing world population and social and economic change mean that more people are vulnerable to volcanic hazard from this source, even at a distance from an eruption.

What’s Happening at Bárðarbunga?

Bárðarbunga is Iceland’s fourth most active volcano. Since the settlement of Iceland in 741, Bárðarbunga has erupted on 43 known occasions – and the figure may be higher. The volcano is located beneath the northern part of Iceland’s Vatnajökull ice cap, which introduces additional hazard in terms of flooding from meltwater as well as increasing the likelihood of an ash cloud as chilled water meets molten rock.

Bárðarbunga’s last confirmed eruption was in 1910, but there have been numerous occasions since 1986 when activity (mainly flooding) has been observed, so the volcano is clearly currently active. Historic evidence suggests that it is capable of very large eruptions indeed: that of 1477 is among the largest of historic times and may have been ten times larger than the eruption of Mt St Helen’s in 1980.

Recent reports form the Icelandic Meteorological Office (IMO) point to continuing unrest at the volcano, with an intense earthquake swarm occurring beneath the ice, indicating that there is some magmatic movement beneath the volcano. At the time of writing a newly-reported tremor of M4.0 shows that activity may be intensifying.

Although the IMO is at pains to stress that “there is no unequivocal indication that magma has reached the surface” (in other words, there is no proof that an eruption has occurred beneath the ice) they also conclude that the seismic activity and other monitoring “indicate magma movements in Bárðarbunga. Due to increased seismicity IMO has decided to turn volcano Bárðarbunga status to yellow on the aviation colour code map. In case of a sub-aerial eruption, an ash plume of potential concerns for aviation will be generated.”

The Eyjafjallajökull Eruption of 2010

Eyjafjallajökull, less active and often overlooked, erupted in April 2010 to dramatic effect. An initially quiet eruption developed dramatically as meltwater interacted explosively with lava, generating an ash plume which carried unusually fine ash across the north Atlantic to the western and northern coasts of Europe, affecting 25 European countries and causing closure of commercial airspace which lasted a week.

Estimates put the number of flights disrupted at over 100,000; the number of stranded passengers in excess of direct losses of 4 million; and the direct cost at at least €1.3bn.

In many ways, the Eyjafjallajökull eruption was exceptional. The ash was unusually fine and therefore capable of being carried a greater distance than normal; and atypical weather conditions assisted with its transport across the Atlantic and a longer-than-usual period in which it remained airborne. But it provides a reminder of the vulnerability of large parts of the northern hemisphere to an eruption on so crucial a transatlantic route.

Looking Forward: What May Happen With Bárðarbunga?

Volcanic eruptions are unpredictable at the best of times. In Iceland, with its different sources of volcanism, and complicating factors of ice sheets which both obscure activity and increase explosivity, they’re even more so. There’s clear evidence that something is happening beneath the ice, but seismic activity does not necessary lead to an eruption; magma movement may cease before the molten rock reaches the surface.

What is certain is that volcanoes will continue to erupt; that large eruptions are probable; and that Bárðarbunga is a prime candidate for an eruption which may have far-reaching impacts — even if the activity of August 2014 does not culminate in an imminent eruption