Monday, March 22, 2010

Fire in Iceland

There has been a torrent of news and information on a volcanic eruption that started Saturday night in Iceland, at a site called Eyjafjallajokull, and the above photo from Der Spiegel (Photo gallery, article) finally spurred me to put together some of the ones I've read. (Side note: the location in English would be "Eyjafjalla Glacier." In Icelandic the meaning of the name Jokull is: An ice glacier, and baby boys are sometimes given that name, which seems a rather cold-hearted thing to do to a kid. Heh.)

The Christian Science Monitor makes an uncharacteristic goof with this:
There are three main places where volcanoes normally occur — along strike-slip faults such as California's San Andreas fault line, along areas where plates overlap one another such as in the Philippines and the Pacific Rim, and in areas like Iceland, where two of the Earth's plates are moving apart from each other in a so-called spreading system.
Strike-slip faults are not especially associated with volcanism (though volcanism can arise there if a fault is offset in such a way as to create a tensional setting); I suspect this is a result of a misunderstanding. The correct three would be subduction (not just "plates overlapping"), rifting, and hot spots, like Hawaii. Iceland has the latter two settings: a hot spot under the mid-Atlantic Ridge. Despite the error, it's an overall good article, describing the concerns that the fissure eruption might spread, and lead to "a larger explosion at the nearby Katla volcano." In the following Flash Earth image (click for full-size), the central cross-hairs are on the approximate location of the eruption; Katla is under the large ice sheet to the east. An eruption there would be... ahhh... messy.And in the following Google Earth image, you can see why I liked the above better, but you can also see a scale bar. This one is backed out a little further, so you can get a sense of scale of the ice sheet on Katla.
Discovery News doesn't have a whole lot of information, but a couple of excellent pictures, one of which is above. The Water Seems Inviting (German) offers what looks to be the more precise location in a SPOT image, but I can't read German, so I'm not positive I'm understanding this correctly.Amphibol (also in German) was the first place I saw this video clip, though I've seen it at numerous other places since:

As always, the go-to information sources on volcanism are Eric Klemetti's Eruptions blog (label Eyjafjallajokull) and The Volcanism Blog (label Eyjafjallajokull). Of particular interest to me was this comment at Eruptions yesterday: "In many "curtain of fire" eruptions on Hawai`i, the curtain (see below) eventually coalesces into a single fire fountain, sometimes producing fountains that can reach a few kilometers in height." Emphasis mine, but Yowza! There are also a couple of videos from Saturday night-Sunday morning here and here, with numerous "related videos" in the sidebar (though I suspect many are repeats)

Many of the news stories seem like press release/wire feed clones (I think the CSM piece near the top is an AP story), so I won't bore you with repetitive links and summaries. But the take-away story as I read it right now is that this is currently a fairly small and gentle eruption. The probability of casualties is low; ~500 people in the vicinity have been evacuated. However, fissure eruptions can spread laterally, and if this one does so under glacial ice, there is real potential for massively destructive phreatic (steam-driven) explosions, or, even more likely, sub-glacial floods, called jokulhaups (there's that "jokul" word again). So even though right now it's pretty harmless and pretty pretty, Eyjafjallajökull is one to keep an eye on.

Followup: The Telegraph has also posted a gallery of photos, of varying relevance to this particular eruption, but illustrating a variety of Iceland's volcanic and volcano-related features.


pygalgia said...

I bet that story broke your spellcheck.
Thank you! I enjoyed reading that.

Silver Fox said...

Haha - spellcheck. Great summary!