The unpredictable fire-mountains of Iceland

Things on my mind: Moving house. So much work at the Museum. LAVA!!

Iceland is erupting. As I write, there is lava pouring out of the barren ground between Europe’s largest glacier and a volcano that erupted so powerfully in 1875 that it caused a mass emigration out of Iceland. But I had to check the webcam before I wrote that, because the activity in the region has been stop-start, repeatedly getting my hopes up and breaking my heart. (One of my friends has taken to calling it ‘Trollcano’.)

It all started two weeks ago, when seismic activity in the region began ramping up, to the tune of thousands of earthquakes to date. At first, the quakes were centred around Bardarbunga, a large volcano under the northern edge of the Vatnajokull icecap. Iceland’s active volcanoes are arranged along the ocean ridge that defines the plate boundary, but each of the major ‘central’ volcanoes also has a little rift system associated with it (the orange stripes on the map below).

The volcanic geology of Iceland. Ignore the fact that Grimsvotn is in bold. That guy isn’t important here!

The Bardarbunga quakes started at the central volcano then started migrating northeast along the rift zone. Tremors concentrated in this way mean magma on the move. When magma moves along a track underground like this we call it a dyke. This dyke quickly took a turn to the north and started running towards the rift associated with the Askja volcano (the 1875 culprit).

While this was going on, on the 23rd August a small eruption in the Bardarbunga volcano was suspected. I say suspected because it was under hundreds of metres of ice, and it’s pretty difficult to tell for sure. No floods came out from under the glacier, and it didn’t melt through the ice, so there was only any real confirmation when a flight over the glacier a few days later noted depressions in the ice.

Earthquakes since 16th August. From the Icelandic Met Office.

At this point, there were four possible scenarios:

Scenario 1. The dyke stops moving, the magma cools and solidifies underground. The seismicity drops off in Bardarbunga, and there’s no eruption.

Scenario 2. The propagating dyke breaks the surface and a lava eruption ensues (at this point it was still beneath the tongue of the glacier, but it has since moved beyond into the plains). This scenario has two possibilities:
a) A series of small-medium fissure eruptions, with fire fountains and lava, analogous to the Krafla fires of 1975-84.
b) A massive outpouring of lava like the 1783 Laki fires that lasted for 8 months. This event produced the largest volume of lava on Earth in the last 1,000 years, devastated crops and livestock in Iceland, and is theorized to have contributed to the French Revolution as crop failures spread across Europe. It also came from the same sub-Vantajokull system that’s grumbling now.

Scenario 3.  The Bardarbunga central volcano erupts. There is still significant magma underneath the volcano and an eruption similar to Eyjafjallajokull 2010 (the no-planes-in-Europe one) or any of the recent events at the nearby Grimsvotn could take place.

Scenario 4. The dyke reaches the Askja system. The Askja volcano has a habit of erupting pretty explosively, due to the type of magma it hosts. Volcanologists suspect there is still a volume of ‘eruptable magma’  beneath Askja – magma that is not moving itself but could be prodded into action by other magma moving in. At this time, the dyke was moving at a steady rate towards the Askja central volcano and might have been expected to reach it by now.

So what did happen? Well, I was truly excited on the 29th August when a small fissure eruption broke out overnight. It lasted four hours.

Then, a new larger fissure eruption started on the 31st August, with fire fountains up to 60 metres in height. At present, it is still going strong, but there is already speculation that the power is dying down.

What’s going to happen next? That’s been the question volcanologists in Iceland and abroad have been bombarded with since the whole episode began. In all the blogs and news from institutions I’ve read over the fortnight, the consensus seems to be that the event is unprecedented, and while at various times one scenario or the other has seemed more or less likely, the path of the future eruption is unknown.

Scenario 1 is clearly ruled out now that lava is flowing. While the fissure eruptions of the past couple of days would point to Scenario 2, it doesn’t mean the other scenarios are out of the question. Before the subglacial eruption of Eyjafjallajokull in 2010 that spat ash across European airspace, there was a beautiful fire-fountaining episode at nearby Fimmvorduhals.

*

Sometimes, I dream in volcanoes. Lately, I wake up every day and wonder what’s happening around Bardarbunga. I watch videos of the flaming plumes feeding slow-moving crisps and crusts of cooling lava. I check the earthquake maps, and the latest 3D visualisation of the situation underground. I check blogs by experts, follow the facebook page of the University of Iceland’s Institute of Earth Sciences, and scan the dedicated volcano feed of the Icelandic media.

Lava is beautiful and mesmerising. Iceland is a place dear to me. (It’s where I studied a year abroad and came top of the class in volcanology, pursuing the study of fire mountains on my return. In the end academia wasn’t the path for me, but I’ll always love Iceland and its volcanoes.) But the timing hasn’t yet worked out for me to have that (secular) spiritual experience of seeing one of Iceland’s own go up in flames and ash and glowing rock. This time, the cost of moving house prevents me from blowing my wages on a plane ticket and booking it to the centre of the action.

If any of you happen to win the lottery, think of me, eh?

For now, here are some stunning images from the University of Iceland’s Institute of Earth Sciences (and my old prof the indomitable Armann Hoskuldsson):

Holuhrain
© Armann Hoskuldsson / University of Iceland
Holuhraun
© Armann Hoskuldsson / University of Iceland
Holuhraun
© Armann Hoskuldsson / University of Iceland

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