Saturday, April 17, 2010

Silent Skies....Eyjafjallajokull

Most unreal in the hills this morning (Saturday) with silent, contrail free skies..... possibly at times despite the westerly blow, just, but only just a hint of sulphurous odour across the normally untainted air at 1400 / 1500ft... just like a distant foundry Lancashire way... recalling a similar but much more dangerous situation of fallout from the skies in early May 1986 after Chernobyl.... but that really did make the fillings in your teeth tingle!!

I know to date and time that this has been reported as an upper air event, but it is noteable as I write that the isobars on the current surface chart show potential airflows direct from the stricken area of south west Iceland into this part of W Yorks, so we will have to see?.... hope the Whoopers make it!


REYKJAVIK, Iceland 2010-04-14 / 2010-04-17 (The situation so far)

A volcano under a glacier in Iceland erupted Wednesday for the second time in less than a month, melting ice, shooting smoke and steam into the air, closing a major road and forcing hundreds of people to flee rising floodwaters.

The volcano Eyjafjallajokull, has been erupting since March, and spewing ash some 20,000 to 30,000 feet into the air. The ash can even be seen from space. Unlike other volcanoes, it is covered by a glacier, so it is creating a lot of steam too.

Authorities evacuated 800 residents from around the Eyjafjallajokull glacier as rivers rose by up to 10 feet.

Emergency officials and scientists said the eruption under the ice cap was 10 to 20 times more powerful than one last month, and carried a much greater risk of widespread flooding.

"This is a very much more violent eruption, because it's interacting with ice and water," said Andy Russell, an expert in glacial flooding at the University of Newcastle in northern England. "It becomes much more explosive, instead of a nice lava flow oozing out of the ground."

Rognvaldur Olafsson, a chief inspector for the Icelandic Civil Protection Agency, said no lives or properties were in immediate danger. Scientists said there was no sign of increased activity at the much larger Katla volcano nearby.

The agency said commercial aircraft had reported seeing steam plumes rising thousands of feet (meters) into the air. Scientists aboard a Coast Guard plane that flew over the volcano said the new fissure appeared to be up to 1.2 miles long.

There were no immediate signs of large clouds of volcanic ash, which could disrupt air travel between Europe and North America. Some domestic flights were canceled, but Iceland's international airport remained open.

The volcano, about 75 miles east of Reykjavik, erupted March 20 after almost 200 years of silence.

The original eruption petered out earlier this week. But Gunnar Gudmunsson, a geophysicist at the Icelandic Meteorological Office, said there were a series of tremors overnight, and rivers in the area began rising Wednesday morning — strong evidence of a new eruption under the glacier.

Last month's eruption struck near the glacier in an area that had no ice. Gudmunsson said the new eruption appeared to be about five to six miles west of the original fissure.

"Most probably this eruption is taking place at the summit … under the ice," he said.

Pall Einarsson, a geophysicist at the University of Iceland, said magma was melting a hole in the 650-foot (200 meter) thick ice covering the volcano's crater, sending floodwater coursing down the glacier into lowland areas.

Residents were evacuated to a Red Cross center in the nearby community of Hvolsvollur, the Civil Protection Agency said.

Iceland's main coastal ring road was closed near the volcano, and workers smashed a hole in the highway in a bid to give the rushing water a clear route to the coast and prevent a major bridge from being swept away.

Iceland, a nation of 320,000 people, sits on a large volcanic hot spot in the Atlantic's mid-oceanic ridge. Volcanic eruptions are often triggered by seismic activity when the Earth's plates move and when magma from deep underground pushes its way to the surface.

The last time there was an eruption near the 100-square-mile Eyjafjallajokull glacier was in 1821.

A bigger worry is Katla, which in the past has erupted in tandem with Eyjafjallajokull.

Katla is located under the vast Myrdalsjokull ice cap. An eruption could cause widespread flooding and disrupt air traffic between Europe and North America.

The last major eruption took place in 1918, and vulcanologists say a new blast is overdue.

"So far there have been no signs of the reawakening of the Katla volcano, but a lot of things can still happen, so we are monitoring it quite closely," Einarsson said.

By the following day... Thursday....An immense plume of volcanic ash cast a silent pall over the skies of Northern Europe on Thursday, grounding air traffic across Britain, Scandinavia and elsewhere, halting flights to and from North America, stranding travelers and isolating much of the continent to an extent that was without precedent in recent memory.

The culprit: an Icelandic volcano that could continue spewing grit into the atmosphere for months or years to come, experts said, although presumably without a continuing effect on air traffic. However, geologists said it was impossible to predict the behavior of the Eyjafjallajokull volcano, or the prevailing winds.

The material spewed by the volcano consists of fine, sharp-edged particles of rock and glass, most of them ranging in size from about one-twelfth of an inch in diameter down to about 1/25,000th of an inch, and they are capable of circulating in the upper atmosphere for months. If they are inhaled by humans or animals, they can damage air passages.The Health Protection Agency said the ash from the Eyjafjallajoekull eruption did not pose a significant risk to public health because of its high altitude. If they are sucked in by a jet engine, they can shut the engine down.

Eurocontrol, Europe's air traffic control organization, said flights could be disrupted through Saturday and beyond. A lack of wind meant the cloud remained dense and was drifting slowly to the east.

Volcanic eruptions "are such a complicated natural phenomenon that almost every one is unique . . . and the amount of ash produced during a given eruption or the length of the eruption is really something that we can't predict," said Earth scientist Olivier Bachmann of the University of Washington.

About 4,000 flights were canceled in Europe on Thursday, said Kyla Evans of Eurocontrol. The number could rise to 6,000 on Friday, she said, plus half of all transatlantic flights.

Airports began closing in Britain at 7 a.m. Thursday as the threatening sulfuric cloud began to reach northern Scotland. Among the first to feel the effect directly were residents of the western Norwegian city of Bergen, who began to complain of a strong sulfuric smell about 1 p.m.

By late afternoon, all airports in Britain, Ireland, Norway, Sweden and Denmark had been shut down. Finland also closed several of its airports. According to Scandinavian airline SAS, nearly three-quarters of its flights, 635 in all, had been canceled.

Cancellations were also reported in northern Germany, Belgium, the Netherlands, Switzerland and France, where the Charles de Gaulle airport in Paris was shut down. Ripples spread worldwide, as flights to Europe were canceled and flights from Europe failed to arrive. Several flights from the United States were forced to turn back.

Scientists say that because the volcano is situated below a glacial ice cap, the magma is being cooled quickly, causing explosions and plumes of grit that can be catastrophic to plane engines if prevailing winds are right.

"The activity has been quite vigorous overnight, (Friday / Saturday) causing the eruption column to grow," Icelandic geologist Magnus Tumi Gudmundsson told The Associated Press on Saturday. "It's the magma mixing with the water that creates the explosivity. Unfortunately, there doesn't seem to be an end in sight."

An expansive cloud of grit hovered over parts of western Europe on Saturday, triggering extended flight bans that stranded people around the globe. Continued volcanic activity could produce more plumes if the weather patterns stay the same.

The Icelandic Meteorological Office said the amount of ash in the plume grew Saturday and that the vast ash cloud is continuing to travel south and southeast.


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