Saturday, April 24, 2010

[Geology2] Eyjafjallajokull Update -- April 24, 2010

Iceland volcano update

The power of the Eyjafjallajokull eruption has remained stable for at least the last two days according to emergency co-ordinators in South Iceland. The volcanic cloud has swung round to the northwest of the glacier today, but there is little ash fall. The cloud has become lighter in colour, indicating more steam and less ash.

The Icelandic Meteorological Office predicts slowly increasing south-easterly winds today blowing the cloud north and west. A small amount of ash could potentially affect Reykjavik, and reduce driving visibility – but that has not happened yet. There is some ash fall on Fljotshlid and will continue to the northwest of the glacier.

Police in Hvolsvollur are reminding the public that all non-emergency foot and car traffic is banned near the volcano: all over Eyjafjallajokull and its foothills, Fimmvorduhals and Myrdalsjokull. The Route 1 highway is open, however.

Meanwhile, with ash closing Keflavik International Airport, there has been a massive increase in passengers using Akureyri Airport, RUV reports. Icelandair and Iceland Express have both been using Akureyri today in order to avoid cancelling flights outright.

Iceland Express flight to Berlin and Copenhagen today have been merged into one flight from Akureyri which will stop in both destinations. Passengers are being taken by coach between Reykjavik and Akureyri.

Icelandair is using Akureyri as its Iceland hub today; but passengers whose final destination is not Icelland are being taken through Glasgow instead of Keflavik.

The Reykjavik domestic airport has now reopened and flights within Iceland are not as delayed as had been feared.


Updated April 23, 2010

Amazing Video Shows Shockwaves Explode From Volcano

By Jeremy A. Kaplan


A stunning new video of Iceland's rumbling, smoking volcano shows rainbow-like shockwaves belching from the crater like snakes from a can of nuts. 

A stunning new video of Iceland's rumbling, smoking volcano Eyjafjallajokull shows rainbow-like shockwaves belching from the crater like snakes from a can of nuts. 

Nothing to fear, though, it's merely the aftereffects of Plinian events.

While rarely captured this well on film, they're not uncommon, according to vulcanologist Jim Quick, associate vice president for research and dean of grad studies at Southern Methodist University. Quick was coordinator of the volcano hazards program with the USGS, and says he's seen shockwaves like this before himself -- in person. 

"We were standing on the slopes of Anatahan in the Marianas Islands," he explains, putting a series of monitoring stations around the remote Pacific island. "There were a series of these explosions hurling giant boulders above the rim. And before you could feel the shockwave, you'd see it as a series of rainbow-like structures just like this. "

Quick explained that in a vulcanian eruption like that going on at Eyjafjallajokull -- the term describes a volcano exhibiting a series of explosive bursts -- you'll see explosions called Plinian events, after the historian Pliny who described the eruption of Vesuvius in 79 AD.

These events are essentially explosive releases of gas. "You have volcanic gases that are held by the magma as it rises toward the surface. Eventually you get to the point where the gases separate from the magma, like popping the top from a soda bottle," Quick explains.

The gases expand rapidly and separate from the magma, causing explosive bursts of tremendous magnitude equivalent to a significant dynamite explosion. As the video shows, the explosion hurls incandescent blobs of lava hundreds of feet into the air -- and cause visible shockwaves.

These shockwaves reflect off the floor and the walls of the crater, shaking the entire surrounding area. In the Marianas Islands, Quick says he could feel the shockwaves rumbling beneath his feet.

"We were half a mile from the actual crater rim, and you could feel it."

Visible shockwaves aren't uncommon, occurring with any volcano having an explosive eruption, Quick explained. On the smaller scale, Plinian events cause them and lead to ejecting blobs of lava.

But Quick notes that such rumbles can have much greater ramifications.

"On the larger scale, they cause Plinian eruptions like Mt. St Helen in 1981," he pointed out.

Video at Source

More video here

(Gars O'Higgins Station penguins)
(Twilight Saga commentary)



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