The Öræfajökull volcano in Iceland is showing signs of activity this month, bringing interest and intrigue to the long dormant volcano whose last known eruption was in 1727-1728. Like many other volcanoes in Iceland, Öræfajökull, the country’s tallest volcano, is mostly buried underneath glacier. The recent activity has caused a large depression in the ice, forming what is referred to as an ice cauldron or subsidence bowl.
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The presence of ice could cause an eruption to be phreatomagmatic, which refers to a reaction of magma with ice that causes steam to be released. According to Benjamin Edwards, a volcanologist at Dickinson College in Carlisle, Pennsylvania, “Even a small eruption will likely produce significant melting given the amount of ice in the summit caldera, and in an environment where water can’t leave the area around the volcanic vent rapidly it will probably cause phreatomagmatic eruptions, which are highly explosive.”
It is difficult to know what caused the ice cauldron to form because of limitations in instrumentation, though subglacial eruptions can still be detected through seismic signatures also known as eruption tremors. According to Dave McGarvie, professor at Open University in Milton Keynes, England, the cauldron could be formed due to a small amount of magma that was released or simply from rising heat. He added, “What can be said with certainty is that the presence of a heat source beneath the ice-filled caldera of this volcano is highly unusual. No subsidence bowl in the ice of this caldera has been recorded in the past few centuries.” Cauldrons are found throughout Iceland and have the potential to cause floods. “There are numerous examples of subsidence bowls in Icelandic glaciers that appear to be caused purely by heating– such as those at the ice-covered Katla volcano, and the famous Skaftá cauldrons, which drain periodically and create sizeable glacial outburst floods.”
For this reason, scientists believe Öraefajökull has started to wake up. “Whether she’s just rolling over in her sleep, or getting ready to fully waken up– nobody knows. It’s too early to tell,” McGarvie added.
Past eruptions from Öræfajökull have been devastating and helped give the volcano the first part of its Icelandic name, roughly translating to wasteland, wilderness, or desolation, which describes the post-eruption surrounding region (the second half, “jökull” means glacier). M Jackson, a geographer and glaciologist who has done research on Iceland said, “The idea of Öræfajökull erupting is terrifying, especially when you put it the historical context. When Iceland was settled over 1,000 years ago, the area around Öræfajökull was verdant and forested, but in 1362 the volcano underneath the glacier Öræfajökull erupted, triggering catastrophic jökulhlaups [type of glacier lake outburst flood] that flooded and decimated the entire region.”
Last week saw record number of earthquakes in Öræfajökull volcano: 160 small tremors. Clear indications Iceland's second deadliest volcano is stirring from its 290 year slumber #Öræfajökull #volcano #Icelandhttps://t.co/zcldAvbpH5 pic.twitter.com/7GrEVjboPf
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Iceland has plans in place if Öræfajökull erupts including partially closing the ring road which encircles the country and links all the major settlements. Gísli Pálsson, a professor of anthropology at the University of Iceland, explained that if an eruption does occur, an immediate alert will be sent to nearby communities with requests for evacuation of farming communities and possibly the town of Höfn and the village of Kirkjubæjarklaustur. ”The worst scenario would be heavy floods and massive clouds and layers of ash,” he said.
The Icelandic government and community is well-prepared in case an eruption does occur. “Volcanic activity in Iceland is ongoing, and embedded in the social fabric of Icelandic society,” said Jackson. “Volcanic activity is reported in the news regularly, and people are vigilant. The government monitors all activity intensely, and the system is highly functional. When I lived in Iceland, I was impressed how often I received alerts for any activity, such as earthquakes, gas leaks, and floods.”
The interaction between melting glaciers and erupting volcanoes can be causal as well. Pálsson said it seems likely that with the thinning of the glacier, a circular pattern is established and eruptions will be more frequent than before, resulting in further thinning of the glacier. “An interesting and possibly devastating spinoff from global warming,” he said.
According to Jackson, Iceland’s largest icecap, Vatnajökull, is located above a hotspot, with many volcanoes buried underneath glaciers. In the last eight hundred years, Vatnajökull has experienced over eighty subglacial volcanic eruptions alone, she said. Many scientists speculate that as Vatnajökull increasingly melts, the rate of volcanic eruptions and earthquakes will increase. “The material products of increased volcanic activity are likely to have long lasting effects on Icelandic society,” she said.
In 2010, Iceland’s Eyjafjallajökull volcano eruption released ash clouds that disrupted air travel in and throughout Europe for an entire week. Öræfajökull could erupt a similar ash cloud, as could other volcanoes in Iceland. With climate change potentially increasing the frequency of eruptions, the world has one more important reason to quickly mitigate the effects of climate change.