On Volcanoes in Iceland

Peddling Fear of an Icelandic Volcanic Eruption

 

The 2010 eruption of Eyjafjallajökull seen on May 8 of that year. Since then, the news media wants us to live in fear of the next Iceland eruption. Image: NASA.

 

As we approach the second anniversary of the Eyjafjallajökull eruption that created air travel havoc across Europe, I suppose it comes as no surprise that the news media has decided to mark the anniversary with fear. I’ve seen a flurry of articles come out over the past few days all pushing the idea that a new eruption in Iceland, bigger and badder that Eyjafjallajökull, is around the corner, waiting to mug you and steal your wallet.

 

Let’s take a quick tour of some of the headlines, shall we?

Really pitching the soft sell, aren’t they? And guess what? Almost every one of these articles focuses on the Big Bad Wolf of Iceland, Katla. Sure, other volcanoes also show signs of activity (see Askja or even2011 eruption of Grimsvötn), but Katla is the media darling. Katla has definitely had large eruptions in the past, but it isn’t even the standard for large eruptions in Iceland (I think the Laki eruption might have something to say about that). However, Katla is (a) near Eyjafjallajökull; (b) hasn’t erupted in a long time; and (c) easier to pronounce.

Now listen, Iceland is a very geologically active place. It sits on the Mid-Atlantic Ridge, were new oceanic crust is born, pushing North America and Europe further apart. It also sits on top of a mantle plume, where hot, buoyant mantle material rises and melts as a decompresses. Both of these factors mean that Iceland has a lot of volcanic activity. It also means many of the volcanoes will appear “restless” as magma moves in conduits under the volcano, sometimes at depths of 30 or more kilometers below the surface – and although magma is moving, it doesn’t mean an eruption is going to happen next week. Volcanoes are dynamic features that are always responding to new intrusions of magma, but remember this key fact: volcanoes spend much more time not erupting than erupting.

This key idea is what makes volcano monitoring such a challenge – we can see the signs of activity, like earthquakes, degassing, warming of the Earth’s surface, steam explosions, deformation, but deciding that volcano X will erupt on a specific date far in the future is just not possible. Sure, we can say the probability is higher that a volcano will erupt if it shows some of these signs, but really, for any active volcano, for each day that passes, we are closer to its next eruption (whenever that might be). Katla will erupt again, but do we need to rehash the fear of total Airtravelopocalypse each time it hiccups? I sure hope not.

The two things we really don’t know about the next eruption of Katla: (1) when it is going to happen and (2) how big will it be. Without this knowledge, all this wailing and gnashing of teeth is for one reason only – to get people to read your article. There is no scientific basis for you to be any more afraid of Katla now than at any time – and even if the signs of activity increase, the fear shouldn’t come with it. As an example, the 2011 eruption of Grimsvötn was, in many times, larger than the Eyjafjallajökull eruption – taller plume, higher rate of eruption (initially) – but it did not cause anywhere close to the chaos that Eyjafjallajökull caused in European/North American air traffic.

What I’m trying to get across is this: Every eruption in Iceland is not doom. Every rumble of a volcano is not a sign of a “huge new eruption”. We live on a geologically active planet and significant geologic events are going to happen (just look at the earthquakes in Indonesia and Mexico yesterday). However, living in fear of that big eruption or that big earthquake isn’t going to help us be prepared for the next one.

Image: Aqua image of Eyjafjallajokull erupting on May 8, 2010. Image by NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team   

from:   http://www.wired.com/wiredscience/2012/04/peddling-fear-of-an-icelandic-volcanic-eruption/#more-105989

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