Thursday, April 22, 2010


Okay, since we've talked about tortadas, Joe Strummer, and Tammy Wynette this week, let's move on to volcanoes.

Like many of you, my interest in voclanoes took a surge with the recent eruptions of Eyjafjallajokull (pronounced "EYE-a-fyat-la-jo-kutl," not that any of us can), and I was very curious as to the effects on Europe if it's sister volvano, Katla, erupted.

Enter Dubious Quality's Geologic Advisor, Ben Pope, who gave me a ton of interesting information over the course of a few e-mails, so let me share some of it with you.

First off, in a geological sense, he writes this:
Iceland is a fantastic, active, terrifying place.

Next, the case for an upcoming eruption of Katla:
As you probably know from some googling, yes, there appears to be a link between Eyjafjoll and Katla with regards to eruptions. Every time it's erupted in recorded history, Katla has also erupted. Of course, in this case 'every' is a sample size of three, and only one of those post-dates the American revolution, but there you go. There've been earthquake swarms beneath Eyjafjoll for the last few months, and an article in February noted significant crustal distension and movement related to the change in the magma chamber directly beneath Eyjafjoll.

It's interesting to note that this means the recent eruptions were effectively expected a few months ago. While it's difficult tp pinpoint the day, "within the next few weeks" is as close to perfect as can be, and the small jokulhlaup caused by the eruption was avoided with prompt evacuation thanks to this information.

He also, though, makes a case against:
There's been movement in the Eyjafjoll chamber, yes, and all the predictives were there for an eruption some time this spring. That said, I can't seem to find any information on recent activity at Katla, and nothing from the reports I can find implies the predictive events at Eyjafjoll are linking to or triggering things nearer to Katla. In fact, the earthquakes seem to indicate that movement in the chamber is primarily on the opposite side from Katla.

The worry seems to be stemming in this case from two primary sources. Firstly, the historic record of twinned eruption in the sites. This is honestly somewhat damning, but circumstantial at best.

Secondly, the fact that Katla is and has always been a terrifying, unstable volcano. It's much larger, Where Eyjafjoll has erupted three times in the last thousand or so years, Katla's got twenty-five confirmed and counting. It appears to have a hair-trigger and a mean temper, for all that you can anthropomorphize a mountain.

My boss mentioned the VEI (Volcanic Explosivity Index), a logarithmic measure, so a "5" on the scale is 10x larger than a "4."

Katla, on the scale, has generally erupted at the 4 or 5 level, historically. For context, the Mt. St. Helen's eruption in 1980 is also classified as a 5, as well as Mt. Hudson (Chile) in 1991.

According to the Wikipedia page, eruptions from 2-5 on the scale have occurred almost 5,000 times in the last 10,000 years (based on data from the Global Volcanism Program of the Smithsonian Institute).

Above that, though, there have only been 56 in the last hundred centuries. So a 6 is a very, very rare occurrence. Mt. Pinatubo in the Phillipines  in 1991 was the last eruption of this size, and before that, you have to go all the way back to 1912.

Looking for a 7? Try Mt. Tambora (Indonesia) in 1815.
The eruption happened at around 7pm, when three columns of flames reaching heights of 40km were first sighted. Two hundred million tonnes of sulphur dioxide and 100 cubic km of rock were released.

The explosion was heard over a thousand miles away,

The after effects were devastating
During the summer of 1816, unexpected climate changes left countries in the Northern Hemisphere suffering from devastating famine and epidemic outbreaks. These weather patterns were the result of the volcanic eruption of Mount Tambora in Sumbawa, Indonesia, on 10th April 1815.

Over the following year, heavy ash-fall filled the air across the globe, preventing sunrays from reaching the earth. The resulting frost and rains devastated crops and caused the “Year without Summer”.

The death toll outside Indonesia ran into hundreds of thousands. With the 117,000 victims who died in the original cataclysm in Indonesia, this was one of the deadliest disasters in history.

In other words, a 7 would put us in deep, deep trouble. Not as much, trouble, though, as we'd be in if the Yellowstone (yes, the park) Caldera erupted :
The last time that beast woke up - with a roar - was 640,000 years ago. That was a supervolcanic eruption that ejected 1,000 cubic kilometers of ash and lava - 8,000 times what was spewed forth by Mount St. Helens in 1980. The Yellowstone eruption area collapsed upon itself, creating a sunken giant crater or caldera 1,500 square miles in area.

Holy crap. That would be between an 8 and a 9 on the VEI scale.

If you're interested and want to bookmark a few information sources, the weekly activity report of the Global Volcanism Program is a good place to start. If you're specifically interested in Katla, here's a site with a ten-minute updates of tremor levels from monitoring sites near the volcano. And if you just want to see some absolutely spectacular photos of Eyjafjallajokul, Scott Ray sent in a link to a magnificent collection from The Big Dig.

Site Meter