The “seismic swarm” of thousands of earthquakes that’s been rattling the Icelandic highlands for the past few days is getting worse. A 4.5 magnitude quake on Aug. 18 was the strongest to hit the region since 1996. Even more alarmingly, the Icelandic Met Office also reports “very strong indications of ongoing magma movement” at Bárðarbunga (pronounced “Bow-thar-bungah”), a giant volcano, and has issued an “orange alert,” signaling escalating eruption risk, which includes the potential for jökulhlaup, a deluge of melted glacial water, as well as ash emission.
Could this be the beginnings of another Eyjafjallajökull, the Icelandic volcano that erupted in 2010? Dave McGarvie, volcanology professor at the Open University, says that the seismic clusters are far enough away from the heart of the main volcano that it seems unlikely to set off the kind of explosion capable of disrupting global air travel. However, “we know so little about this volcano that she could surprise us,” adds McGarvie.
Let’s hope for no such surprises. When Eyjafjallajökull erupted in 2010, it clogged the atmosphere with so much volcanic ash that at one point the plume was grounding tens of thousands of global commercial airline flights a day.
In just the single month that Eyjafjallajökull’s ash cloud blotted northern European skies, the volcano shaved $4.7 billion off the global economy, according to Oxford Economics (pdf), a research firm.
If the new tremors do end up hitting the heart of Bárðarbunga’s main volcano, where the magma is produced, it could set off an explosion of such fury that it would make Eyjafjallajökull’s 2010 episode look like a smoke ring.
Iceland’s second-highest mountain, Bárðarbunga lies under the northwest part of the Vatnajökull icecap and is part of Iceland’s biggest volcanic system, which extends more than 200 kilometers. The last time it erupted, in 1910, Bárðarbunga was fairly mellow. That’s not always the case, though. Bárðarbunga generated the largest flow of lava in the last 10,000 years. Its 1477 eruption was one of the most explosive ever recorded, scoring a 6 on the “volcanic explosivity index.”
It’s lucky that few people lived in Iceland and neighboring areas back then. Other VEI-6 volcanoes include Krakatoa, which killed at least 30,000 people in 1883, and the 1780s eruption of Laki, another Icelandic volcano. A hundred times more powerful than Eyjafjallajökull, Laki’s eruptions thickened the atmosphere with so much toxic muck that it killed half of Iceland’s livestock, setting off a famine that wiped out a quarter of the country’s population. As Laki’s toxic spew blew southward, it destroyed still more crops, killing 23,000 in Britain, causing famine in Egypt, and inducing enough food poverty in France that some environmental historians think it helped ignite the French Revolution.