Tuesday, January 28, 2014

Iceland's Volcanoes Still Quiet

The land of Ice and Fire, it may be. But for the last few years now, it's been pretty much just Iceland. The last eruption to occur in Iceland took place after the now infamous Eyjafjallajökull eruption, from Grimsvötn (Grimsnes) volcano, which came and went without much fanfare. Since then, aside from some interesting quake activity, the restive continent has been nearly silent. So what gives?

Well, for one thing, volcanoes (contrary to popular belief) aren't on a schedule. Some very specific conditions need to occur for volcanoes to erupt. The eruption of Eyjafjallajökull in April of 2010 was preceded by around a decade of slow magma intrusion, and other volcanoes like Katla are buried under glaciers, which means it takes quite a bit of magma build up to break through the ice and produce an eruption. Katla had a suspected sub-glacial eruption after Eyjafjallajökull's Europe-stopping event, but this was inferred only due to glacial outburst flooding and chemical analysis.

Currently in Iceland, the ice is in full effect as Winter pokes along. It has been speculated that thick ice cover can suppress volcanic activity in Iceland (and maybe, perhaps, is suppressing volcanic activity in Greenland as well, although this has never been proven due to the thickness of the ice sheet), so some scientists suspect that quiet in Iceland could be due to this effect. When the ice retreats, an effect known as 'crustal rebound' is thought to occur, increasing the probability of an eruption, or at the very least, getting out of the way of an imminent one. But it has now been years since the last eruption and one can only wonder, which of these volcanoes will it be next?

Given what I am personally observing over there on seismographs, there seems to be only a couple 'likely' candidates for the near term. Askja volcano has been displaying some weak seismicity, and it is possible it had a slight ash and gas exhalation a couple years back, but this was never confirmed. Hekla volcano is always on everyone's watch list, but nothing unusual has been occurring there. That leaves really only a few more volcanoes over there that have much of a historical record of eruption, and none of them are acting particularly restless at the moment.

Hekla volcano has long been considered to be 'overdue' for a show, as it tends to be one of Iceland's most active. This volcano historically does not give a lot of warning before popping off, so it could indeed be primed for some action, and we simply wouldn't know. It is a complete waste of time with these volcanoes to actually predict WHEN they will go off, but it is certain that they will in the future. Time is the only thing that will tell. If anything, we could probably expect due to the ice cover, that the island may wait until Spring or Summer to show any activity as the ice recedes.

Icleand lies on a spreading fault, a tear in the earth's crust that is pulling the European plate away from the Atlantic plate, opening up fissures and channels for magma to rise up and become lava in an eruption. It is theorized that Iceland is part of a mantle plume system, much like Hawaii, that is positioned directly on this spreading fault, giving it a vast reservoir of magma, and possibly the largest mantle plume on Earth.

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