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Eygló Svala Arnarsdóttir's picture

After six months, the volcanic eruption in Holuhraun came to an end on Friday. Producing material for spectacular photographs and numerous articles, the eruption sure was thrilling to observe, but it’s also a relief that it’s over.

Here’s a brief overview of the developments in the past six months:

The eruption in Holuhraun was preceded by a series of earthquakes which began in Bárðarbunga volcano, which lies under Vatnajökull glacier, on August 16 but gradually moved to the north.

The pattern of earthquakes indicated that magma was channeling its way underground, creating a 50-km long intrusive dike, which ended in the already existing Holuhraun lava field to the north of the glacier.

After a minor eruption which lasted a few hours on August 29, a 1.6-km (1-mile) long fissure opened up on August 31spewing 1,175°C (2,150°F) hot lava from three craters, Suðri, Baugur and Norðri, 100 meters into the air.

The lava spread out over the old lava field, flowing onto the sands and into the riverbed of glacial river Jökulsá á Fjöllum, which retreated. Eventually, the new lava field stopped expanding and started thickening, while the edges around the craters grew taller.

The craters later merged and formed a bubbling lava lake. The eruption remained fairly stable until mid-January. One month later it was reported that the eruption was likely in its final days and on February 27 it came to an end, having lasted almost six months, or 181 days.

Notably, volcanologist Haraldur Sigurðsson predicted in October that the eruption would end on March 4 and was off only by five days.

With the help of his grandson, an engineering student at Reykjavík University, Haraldur based his prediction on a simple math formula calculating the curve of the decreasing subsidence of the Bárðarbunga caldera and hence reduced pressure of magma. It’s the first time in history that the end of a volcanic eruption has been predicted with such accuracy, he says.

Here are a few facts about the eruption:

The Holuhraun eruption is not only the largest lava eruption in Iceland but also the world since the 1783-1784 Laki eruption in Iceland. Holuhraun emitted 1.4 cubic km (49 billion cubic feet) of lava covering 85 square km (33 square miles), which is the same size as Iceland’s largest lake, Þórisvatn. For comparison, Manhattan measures 59 square km.

Holuhraun is also the ‘hottest’ eruption the world has seen this century, at one point releasing one third more energy than Russian volcano Tolbachik, which erupted 2012-2013 and placed second on the list, as concluded in a study led by Robert Wright of the Hawaii Institute of Geophysics and Planetology.

The lava is approximately 40 meters (131 feet) thick at the lava field’s highest points. The crater is 70 meters, almost as tall as the second-tallest building in Iceland and the country’s tallest church, Hallgrímskirkja in Reykjavík, which measures 74.5 meters. The crater is 100 meters wide and 600-700 meters long. The average thickness of the lava is ten to 14 meters.

Scientists disagree whether Bárðarbunga will erupt again in the near future. Haraldur is not convinced, while Ármann Höskuldsson, volcanologist at the University of Iceland’s Earth Sciences Institute, believes we’re looking at a divergence series and that Holuhraun is just the beginning of a series of eruptions.

He points out that it’s similar in nature to Kröflueldar, a series of volcanic events in Northeast Iceland which produced ten eruptions in the nine-year period 1975-1984.

Kristín Jónsdóttir, director of the Icelandic Met Office’s natural hazards division, agrees with Ármann, warning that another and potentially more dangerous eruption may be coming up. Kristín reasons that as a large part of the volcanic system lies under Vatnajökull, a sub-glacial eruption is likely.

While Dettifoss waterfall and Jökulsárgljúfur canyon have been reopened, a large area in the northeastern highlands remains off limits due to the risk of flash flooding.

The situation is being reviewed but the Icelandic Met Office and National Commissioner of the Icelandic Police’s Department of Civil Protection and Emergency Management are keeping a close eye on the volcano.

Volcanic gases are still being emitted at the eruption site, which pose a further risk of gas pollution around the site and in inhabited areas across Iceland, particularly to the north, east and south of Holuhraun. Gas levels are also being monitored closely.

For now, the new lava remains off limits for tourists but in the future, it may prove a new tourist attraction. In the meantime, there are many other destinations worthy of visiting in a safe enough distance from the eruption site.

Eygló Svala Arnarsdóttir – eyglo(at)icelandreview.com

Views expressed here are the author's own and do not necessarily reflect the opinions of Iceland Review.