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Volcanic Behavior

@vicchi says AY-uh-fyat-luh-YOE-kuutl. I say AY-yuh-fyalla-YO-kel. Let’s call the whole thing off. Then again, I call this a row-ter, while he refers to it as a roo-ter. Hmph.

The media and public are all OMG ICELAND VOLCANO ASH CLOUD MEESA SAY PEOPLE GONNA DIE, like it’s never happened before. We geologists were introduced to the term jökulhlaup (yokel-laup) early in our undergraduate days because it has, just not in the Modern Attention Span era. By the way, jökul is Icelandic for any mountain covered by ice and snow, so you can drop it and refer to our currently erupting wonder simply as Eyjafjalla. Phew.

I’ve been asked why Eyjafjalla isn’t playing nice like Hawaiian volcanoes that just ooze all over the place and don’t ground flights (unless your runway is burned off the face of the earth).  One of the reasons is the presence of rhyolite in the magma. In other words, Hawaii’s volcanoes produce basalt, which has an extremely low silica (SiO2) content in comparison with Icelandic volcanoes, which extrude rhyolite with 70+% silica content and water. The presence of silica increases the viscosity of the melt, hence generating explosions and ash. Those of you in the Basin & Range of the United States, take note.

There are other contributors such as where Iceland is located, i.e. on the mid-Atlantic ridge (and apparently a mantle hotspot) and under a giant pile of snow and ice. Ars Technica’s Understanding The Split Personality Of Iceland’s Volcanoes offers a simple and short geologic roundup of all the factors in play here.

Check out the awesome pictures of volcano and ash action at Boston.com’s Big Picture.

NYTimes | A Tale Of Two Volcanoes: Simon Winchester compares and contrasts Krakatoa and Eyjafjalla. In Krakatoa, Winchester explains the geologic and socio-political story surrounding that famous Indonesian volcano and argues that that volcanic activity (along with something about being under the thumbs of imperialist bastards) contributed to the region’s eventual and fierce Islamic revolution.

All of this is to say that active geology can have very sudden, profound and long-lasting effects on human behavior. Just something to keep in mind as volcanologists warn that “ Iceland is entering its next active phase and estimate it will last for 60 years or so, peaking between 2030 and 2040,” hence disrupting North Atlantic air travel.

1 comment… add one
  • Blair April 20, 2010, 4:02 PM

    It was fun to watch governments taking risk-free positions and then being unable to back off for fear of taking responsibility for being the first to relax restrictions.

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