Katla Volcano on the Verge of Major Eruption – Again/Still

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Iceland’s Katla Volcano is, once again, displaying signs of an imminent eruption. Are volcanologists crying wolf? It’s impossible to say, but given the current situation — and with so much at risk — how could they not?

By my count, this is my fifth YourWeatherBlog piece about the Katla volcano since the summer of 2010 (read previous entries here, here, here and — oh yes — here ). Remember, it was April of 2010 when Katla’s neighbor Eyjafjallajökull erupted and brought trans-Atlantic and western European air traffic to a near standstill. The underlying thought was (and is), If Eyjafjallajökull could do that (shut down air traffic), imagine what the larger Katla could do!

The Katla volcano is partially covered by the Mýrdalsjökull glacier. Photo: Wikipedia

And it is larger. By some estimates much larger. Experts cite the last major eruption of Katla in 1918 as being five times larger than 2010’s Eyjafjallajökull which threw volcanic ash miles into the atmosphere and grounded vast amounts of air traffic for six days. Might a major Katla eruption ground air traffic for a longer period and might the ash cloud spread much farther from Iceland? Most experts agree yes and yes. Those experts include ImpactWeather’s in-house geologist Fred Schmude who comments that the next Katla eruption will likely be a VEI (Volcanic Explosivity Index) 5, Plinian-type eruption as compared to the 1918 Katla eruption which was classified as a VEI 4 or perhaps a VEI 5. Eyjafjallajökull’s 2010 eruption was classified as VEI 4.

What does history tell us? It’s not good. Katla, since 930, has erupted 16 times at intervals of 13-95 years. It’s been 94 years since the VEI4/5 eruption of 1918. Presently, this is one of the longest periods of dormancy in its history. One way or another, it seems Katla is about to go into the record books.

The chambers of Katla and its neighbor, Eyjafjallajökull. Image: Wikipedia

What’s the latest? Based on precise GPS measurements, the surface of the volcano is moving erratically. This is an indication that magma is not only pooling in the caldera, but that magma is rising to the surface — both signs that an eruption is imminent. If you’ve browsed the previous Katla postings from YourWeatherBlog, you know another sign of a potentially imminent eruption is an increasingly high frequency of earthquake activity and that, too, is accompanying the rising magma. Interestingly, Katla’s chambers are interconnected to neighboring volcanoes and seismic activity not directly under Katla can sometimes be misdiagnosed as a precursor to a Katla eruption when, in fact, it’s the under-Katla eruptions that must be monitored. I don’t mean to downplay the role of neighboring earthquakes — they are certainly key to the overall instability of the region. However, only two of the under-Katla earthquakes have been recorded in the last 48 hours. “Significant,” says Fred, “but not overly alarming.” At least not yet.

What’s the take-away? Active preparation, no matter the forecast. That’s exactly what I wrote yesterday in an article for YourWeatherBlog concerning the potential for a significant outbreak of severe weather here in the States this weekend and/or early next week. One can’t reroute or delay a hurricane, an ice storm, a tornado or even a volcano. These things happen when they happen. We can, however, be as prepared as possible. Icelandic residents have seen this over and over: Iceland sits at the northern extent of the Mid-Atlantic Ridge which is the tectonic plate boundary of the Eurasian and North American Plates; the visible representation of this ridge is Reykjanes Ridge which dominates Iceland’s landscape. Geology 101 tells us that where plates collide, earthquakes, volcanoes and mountain ranges have a way of popping up on a more or less geologically frequent schedule. I’m very curious to know what steps the residents of Iceland and, more specifically, the residents of Vik have taken to prepare for the imminent eruption. Have they made significant preparations? Or are they like most Americans, even those in so-called risky areas, who haven’t even made basic preparations?

The unanswered eruption question remains: When? (When, not if.)

I’ll keep you posted.

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