Recently, a large number of earthquakes were detected around the Yellowstone caldera in the United States. While the chances of a supervolcano eruption are small, how would Iceland fair in such a catastrophe? To find out, we reached out to physical chemist Dr. Helgi Rafn Hróðmarsson, aka The Cosmic Chemist to find out.
Short answer, everybody probably dies. Long answer. Let’s first define a supervolcano, shall we?
To assess the gravity of the explosiveness of volcanos, the Volcanic Explosivity Index (VEI) is used. The VEI associated with an eruption is dependent on how much volcanic material is thrown out, to what height, and how long it lasts. The VEI indices run from 0 to 8 and it is a logarithmic scale like the Richter scale for measuring the severity of earthquakes. I.e. Going up in index infers a tenfold intensification!
Supervolcanos are classified as VEI-8 but to give a direct comparison to our own backyard, the eruptions in Katla in 1918 and Eyjafjallajökull in 2010 are classified as a measly VEI-4. Imagine 10.000 Eyjafjallajökull eruptions all at once and you get an idea of the kind of infernal apocalypse a supervolcano prophesizes.
Although Yellowstone is pretty far away from Iceland, us Earthlings still share the same climate. Volcanos infamously impact our climate many months and even years after the eruption. (You think the Eyjafjallajökull-caused flight cancellations were bad?)
To understand the climate effects a supervolcano might have, we can do a rough extrapolation of the largest volcano closest to us in time – the eruption of Mount Pinatubo in 1991. Following this eruption (which is classified as VEI-6), an enormous amount of sulfur dioxide was released in the atmosphere, creating a haze of sulfuric acid which spread throughout the stratosphere. The resulting atmospheric injection of acidic aerosols reduced the normal amount of sunlight reaching the Earth’s surface by 10% which led to an average drop in temperature in the Northern Hemisphere by 0.5°C. Even worse, the depletion of the ozone layer was accelerated which led to the lowest ever ozone levels on record.
If these are the effects from a VEI-6 event, could we predict a scenario at least a hundred times worse with a VEI-8 supervolcano? That is difficult to say, but probably yes.
So, what would the long-term effects be for Iceland if Yellowstone erupted? Decades of reduced sunlight and lower temperatures. Ozone layer might be screwed. Ergo, we might be screwed for the long run. Dissipation of sunlight as well as the ozone layer could mean we would have to live underground. Become human naked mole rats. Let us hope it doesn’t come to that.”
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