Wednesday, September 28, 2011

[Geology2] Did Iceland’s Katla volcano erupt under the ice this summer?

Did Iceland's Katla volcano erupt under the ice this summer?

An Icelandic geophysicist says that the Katla volcano probably already erupted this summer without breaking the surface of the glacier.

Einar Kjartansson, a geophysicist with the Icelandic Met Office, believes that a small volcanic eruption at Katla was the reason for this summer's glacial flood in the Mulakvisl river.

When a jokulhlaup flood happens, it is the result of geothermal heat having melted ice, which collects under great pressure before bursting free in a short, sharp flood. They can cause large areas of glacier to subside. When the Mulakvisl flood happened this summer four parts of the Myrdalsjokull glacier sank down. There was also a very sharp subsidence event in the middle of the volcanic crater — a phenomenon the Icelandic Met Office geophysicists had not seen before.

"It is an indication that a very quick melt took place under there," Einar Kjartansson told RUV. "The glacier seems to have melted very quickly from underneath and it is difficult to see how that could have happened unless there had been a small eruption under there."

To back up his theory that Katla erupted this summer, Kjartansson says that when the flooding took place, there was a lot of seismic activity under the glacier, similar to when an eruption is taking place. In fact, he says, there was more seismic activity than during 2010′s Fimmvorduhals eruption.

"That is the second pointer which indicates that molten lava came into contact with the ice under the glacier," Kjartansson says.

If a small Katla eruption did take place this summer, it does not necessarily mean that the pressure inside the volcano dropped significantly, or that another eruption is less likely than it otherwise would have been, the scientist warns.


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