In 2014, researchers captured stunning footage of Iceland’s biggest volcanic eruption in 200 years. The Bárðarbunga eruption spewed a Hiroshima atomic bomb’s worth of energy every two minutes for nearly six months.
A group of seismologists from Cambridge University in the UK monitored it for two weeks, and witnessed the moment it began erupting.
“It was absolutely spectacular,” said Robert Green, a seismologist at the University of Cambridge. “Seeing nature in its absolutely full power was something I will never forget.”
Their work sheds light on how and where volcanoes erupt. “Most people think of a volcano as being a large mountain where molten rock comes straight up from under the ground and erupts directly from the summit, either explosively creating a huge ash cloud, or producing lava which flows down the sides,” Green explained. ”Instead [in Bárðarbunga] the molten rock moved 46 kilometers underground away from the volcano before it emerged in a completely different place. When it did, the eruption formed a curtain of fire the height of Big Ben.”
With volcanos, size in itself doesn’t determine how dangerous or disruptive an eruption is. In 2010, the unpronounceable Eyjafjallajökull eruption in Iceland created a gigantic ash cloud that brought 100,000 flights in and out of Europe to a standstill. On the volcanic explosivity index (VEI), it ranked four for “cataclysmic.” The Bárðarbunga eruption was much bigger, releasing 10 times more energy than Eyjafjallajökull, and on the VEI, it could be ranked six for “colossal.” And, yet, it didn’t cause any flights disruptions.
The plume created by a volcano depends not just on the amount of energy released but also where it is released. Eyjafjallajökull erupted under an ice cap, which meant that when its hot magma came in contact with ice, it created a plume that climbed high into the atmosphere. Combined with the winds at the time, it caused dangerous conditions for flights. Bárðarbunga, on the other hand, didn’t erupt under ice.
To track Bárðarbunga before and after the explosion, the researchers had to navigate one of the most challenging terrains on Earth, so that they could plant devices that could measure the many tiny changes that occur during such natural events. They used snow scooters, four-wheel drives, and helicopters to ensure that they didn’t miss the action.
It was “an utterly surreal experience,” said Jenny Woods, another member of the Cambridge team. “It was a real reminder of the raw power trapped in the Earth beneath our feet.”
Before the Bárðarbunga eruption, the Cambridge team tracked 30,000 mini-earthquakes, and showed how these earthquakes helped the movement of the magma to reach the point where it erupted. That’s how they found where the earth would break.
This kind of monitoring will help improve the early warning systems set up in Iceland to deal with the constant threat of eruptions. More broadly, however, it shows that understanding the geology of the site of possible volcanic eruptions is crucial to better predicting when a dangerous one will happen.
The team’s work will be on display at the Royal Society Summer Science Exhibition in London from July 4 to July 10.