Wednesday, November 23, 2011

[Geology2] Volcano News November 24 2011

Amid simmering speculation, Iceland volcano keeps intentions quiet

Iceland's Katla volcano is always aquiver with seismic activity and local people and scientists have been waiting for an eruption for years — although they probably experienced them this year and in 1999 without even noticing.

There has been increased activity at Katla since early July, when a sharp flood was released from under the Mýrdalsjökull glacier and down the Múlahvísl river, washing a road bridge away; as was widely reported at the time. Katla's unrest has, it seems, entered a new stage, a leading geophysicist says.

Katla is a very unusual volcano in that there is seismic activity in and around nearly all the time. That activity usually comes in stages — the latest of which began in July.

"The most likely explanation for this is that Katla is, in actual fact, always on the brink of erupting. This we saw in 1999, when there seems to have been a small eruption of a similar type to this [latest small eruption this July]. That one was accompanied by unrest and changes to seismic activity and increased geothermal heat in the subsequent years," Páll Einarsson, University of Iceland geophysics professor, told RÚV.

Last year there was significant seismic activity associated with the Eyjafjallajökull eruption, but since this July — when the Múlahvísl flood took place — activity around Katla and the Mýrdalsjökull glacier has increased and changed, Páll says.

He believes that the frequent but irregular small earthquakes are caused by magma intrusions coming from a shallow depth in the crater itself which could lead to an eruption — just as also happened in July and in 1999, he believes. In that regard Katla is just like other volcanoes: "Sometimes it produces big eruptions, sometimes it produces small eruptions, sometimes it produces tiny eruptions; so it is not always a disaster when Katla erupts," Páll says.

(Photos: Ágúst Rafnsson. Taken at Fimmvörðuháls in 2010, for illustration purposes only.)


Air traffic woes thanks to Chile volcano

Thursday November 24, 2011

Flights have been delayed and canceled in Uruguay for a second day in a row due to volcanic ash from the eruption of the Puyehue volcano in Chile.

At Carrasco International 'there was a TACA flight canceled in the early morning, American Airlines delayed its flight coming in from Miami due to ash and then canceled it; and another flight from Rosario (Argentina) was canceled,' an airport official said on Wednesday, adding that the schedule was now closer to normal.

An Iberia flight from Madrid arrived with three hours delay, the official said.

Since the volcano's eruption on June 4, air travel in much of the southern cone of South America, and as far away as Australia, has been periodically disrupted by ash clouds streaming east out of the Chilean Andes.

Authorities in Buenos Aires and Santiago did not report ash related problems on Wednesday.

Chile's National Geology and Mining Service said that ashes from the Puyehue - which continues belching, though at a lower intensity - could affect air travel for months.

The decision to delay or cancel flights is made by the airlines over concern about how the fine ash might affect aircraft engines.



Is the Anak Krakatau Volcano About to Blow? (Video)

November 23, 2011

Indonesia's Mount Anak Krakatau volcano has been puffing white smoke the last few days, and scientists are warning locals and tourists to keep away. That could mean that the long suspected eruption of the world's most famous volcano could be imminent.

Actually, this volcano is the remnant of the biggest blast ever recorded on Earth. That was the 1883 eruption of Mount Krakatoa. From the ruins of that gigantic crater left in the land has come forth what is now known as the Anak Krakatau volcano—literally "Krakatoa's Child."

In the time since the original eruption, scientists have gotten much better at predicting when a volcano will have a catastrophic eruption, distinguishing it from the many smaller eruptions which do not harm the local population or environment.

One of the telltale signs is sudden and increased activity like what scientists are seeing in this past week at the Anak Krakatau volcano.

Of course, not wanting to take unnecessary chances, scientists have to balance warning off residents with calling a false alarm. That's why this recent warning is so significant. Seismologists have learned to read the signs to an astonishingly accurate degree and have a tremendous track record for getting it right.

So, the world may be close to once again hearing the loudest sound ever recorded. And this time, the spectacular show will be caught on tape!

Here's a video of the volcano from just a year ago. Another example of the awesome power of nature.

Video available here at source

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