Activity at Bárðarbunga Volcano: Update, 5 September 2014

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Home / Activity at Bárðarbunga Volcano: Update, 5 September 2014
The fissure eruption at Holohraun. Image credit: Benedict G. Ófeigsson

The fissure eruption at Holohraun. Image credit: Benedict G. Ófeigsson

What’s happening in Iceland? After all the excitement over the possibility of an eruption at Bárðarbunga volcano, the media interest seems to have died down. There was a small eruption, no ash cloud and that was it.

But was it? Volcanic eruptions, especially in Iceland, are complex things, connected to one another at depth and rarely occurring in isolation. As one Tweeter put it: “Any geology student in the world should be on @twitter 2 monitor #Holuhraun #eruption & #Bardarbunga – so many online lessons happening live”.

Bárðarbunga – Latest Update

With magma bubbling up so rapidly from beneath the surface of the Earth the situation changes quickly and information can be almost instantly out of date.

Aviation codes flash from red and orange and back again; roads and airspace are opened and closed; and scientists are evacuated and allowed to return as the situation alters.

Twitter is alive with information on Bárðarbunga. Image from Twitter

Twitter is alive with information on Bárðarbunga. Image from Twitter

Early suggestions of an eruption beneath the ice at Bárðarbunga itself appear not to have come to fruition, but a narrow arm of magma (a dike) propagating to the north did reach the surface to the north.

Rifting produced an eruption along a fissure in the crust and two new fissures opened up on the morning of 5 September. At the time of writing the flow, known as the Holohraun, has covered an estimated 10.8 square km in less than a week.

The Holohraun Lava Field

Iceland’s national broadcaster, Fréttastofa RÚV, quoted volcanologist Armann Hoskuldsson as saying “We estimate the fissure to be about 700 metres long, and the southern end of it is not far away from the margin of Dyngjujokull glacier.”

The significance of this is that the presence of ice not only enhances the likelihood of an explosive eruption (because of the interaction between hot rock and chilled magma) but also produces the very real risk of extensive flooding in the area as vast quantities of ice melt.

Currently, then, there are three fissures producing fire fountains along linear breaks in the crust – to dramatic, and highly photogenic, effect. Although the IMO notes that clouds of steam reach around 15,000 feet in altitude and include “substantial amounts of CO2”, there’s no ash and no risk to aviation.

Iceland Earthquake Activity

Earthquakes at Bárðarbunga volcano. Image credit: IMO

Earthquakes at Bárðarbunga volcano. Image credit: IMO

Movement of magma generates earthquakes and it was an earthquake swarm which first indicated that something was happening beneath the ice. According to the Iceland Meteorological Office’s daily update on 5 September, “About 170 earthquakes were detected since midnight. Two earthquakes of magnitudes 4,4 and 5,3 were detected in the Bárðarbunga caldera region at around midnight UTC.”

The pattern of earthquakes since the beginning of the eruption clearly shows both the location of the dyke and the manner in which it propagated northwestwards and continuing activity around the subglacial caldera of Bárðarbunga itself – indicating that the terrestrial firework display amy not be over.

Bárðarbunga: What Will Happen Next?

Steam rising from the Holohraun lava field. Image credit: IMO

Steam rising from the Holohraun lava field. Image credit: IMO

So great is the complexity of the volcanic plumbing system underlying Iceland, it’s difficult, if not impossible, to predict what will happen next, especially given that the key processes are hidden and many variables are at play (such as the chemical composition of the magma, ice cover or lack of it and interaction with other parts of the volcanic system).

The most recent update from the IMO proposes four scenarios which are more likely than any others (while noting that those other scenarios can’t be ruled out).

One of these scenarios, the opening of a further fissure or fissures, has come to pass since the update was published. A second, with the duke progressing towards the ice, is also looking increasingly likely.

The remaining two alternatives are the extremes but may yet also come to pass. In one case, the eruption may simply die down; or there may be an eruption in the Bárðarbunga caldera which would generate significant flooding and potentially an ash cloud.

Iceland’s volcanologists — and Decoded Science — are watching carefully to see how the situation develops. Watch this space!

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