Iceland Volcano Struck By Biggest Earthquake Yet, Still No Eruption......

Iceland volcano struck by biggest earthquake yet, still no eruption. A warning sign blocks the road to Bardarbunga volcano, some 20 kilometres (12.5 miles) away, in the north-west region of the Vatnajokull glacier August. [clcik image to enlarge] STOCKHOLM (Reuters) - A magnitude 5.7 earthquake hit Iceland's Bardarbunga volcano overnight, the biggest since tremors began 10 days ago, but there is still no sign of an eruption, the country's Meteorological Office said on Tuesday.

Intense seismic activity at Iceland's largest volcano system has raised worries that an eruption could cause another ash cloud like that from the Eyjafjallajokull volcano in 2010 that shut down much of Europe's airspace for six days.

"There was one event during the night ... it was a magnitude 5.7 (quake), the largest in this series," Palni Erlendsson, a geologist at the Met Office said.

"Activity is still deep and we see no signs of anything close to the surface."

On Sunday, Iceland lowered its warning code for possible volcanic disruption to the aviation industry to orange from red, the highest level on the country's five-point alert system, after concluding that seismic activity had not led to a volcanic eruption under the glacier.

Red alert indicates an eruption is imminent or underway with a significant emission of ash likely.

Met Office scientists believe the earthquakes are a result of magma flowing out from under the crater of the volcano, causing a change in pressure.

The migration of magma -- estimated at around 300 million cubic meters (10.6 billion cubic feet) along a 35 kilometer (21 miles) dyke by Icelandic scientists on Monday -- could stop. That should lead to a gradual reduction in seismic activity. But the magma could also reach the surface away from the glacier. This would probably lead to an eruption, but with limited explosive, ash-producing activity, scientists said.

If the magma reaches the surface under the glacier, that would lead to flooding and possibly an explosive eruption and ash production, they added. An eruption inside the Bardarbunga caldera is also possible, but scientists say less likely than the other scenarios.

"We still can't say whether it will cease, continue like this for a while or erupt. It's impossible to say," Erlendsson said.

There have been thousands of smaller quakes over the past week at Bardarbunga. Areas around the volcano, in the center of the North Atlantic island nation, have been evacuated.

Bardarbunga is in a different range to Eyjafjallajokull.Iceland put the Coast Guard on standby and issued a red alert to the aviation industry Saturday after detecting a small subglacial eruption of lava under an ice cap at the Bardarbunga volcano — one of the country's largest.

Data from radar and web cameras show no visible signs of eruption at the surface level that would suggest ash will be shot into the atmosphere. However, Iceland's Meteorological Office is taking all precautions and the red alert level indicates an eruption could occur at any point.

"The rate of earthquakes has increased such that they are happening so quickly that it is difficult for the seismologist to discern individual events," Iceland's Meteorological Office in Reykjavik said in a statement on its website. "The activity continues and an eruption can therefore not be ruled out."

Melissa Pfeffer, a vulcanologist with the Meteorological Office, told the Associated Press that seismic data shows lava from the volcano is melting ice beneath the Vatnajokull glacier, but that it's not still clear whether the volcano will melt the ice, and send steam and ash into the atmosphere.Reykjavik (AFP) - Iceland on Tuesday began evacuating areas close to its largest volcano after warnings of a possible eruption, four years after millions of air travellers were grounded by a huge ash cloud from another peak.

Scientists believe the ash from an eruption at Bardarbunga, a huge volcano under Iceland's largest glacier, the Vatnajokull in the south of the country, could disrupt transatlantic and northern European air traffic.

They also fear floods from melting ice could cause serious damage to the country's infrastructure.

On Tuesday, police announced that they had "decided to close and evacuate the area north of Vatnajokull as a result of seismic activity on the Bardarbunga".

It is not known how many people have been moved as the area is remote, but emergency services in Iceland have been placed on "alert".

The Icelandic Meteorological Office raised its aviation alert to "orange", the second-highest level on Monday after four days of increasing seismic activity, signalling a heightened risk of eruption.

On Monday, seismologists recorded an earthquake of 4.5 on the Richter scale, the strongest in the region since 1996.

Roads in a sparsely populated area north of Bardarbunga were closed on Tuesday, as the Meteorological Office said it had recorded some 2,600 tremors over the past four days.

Bardarbunga, Iceland's second-highest peak, which rises to more than 2,000 metres (6,500 feet), caps the country's largest volcanic system.

It sits in one of the most active seismic areas on the planet.

Bryndis Brandsdottir, a geophysicist at the University of Iceland, told public broadcaster Ruv on Tuesday that the latest readings indicated that magma was not approaching the surface, but rather remaining "three to seven kilometres below".

"We meet twice a day, but the earthquake activity still comes in waves. There do not seem to be any changes, but it is still very powerful," Vidir Reynisson, department manager at Iceland's Civil Protection Department, told broadcaster 365.

In 2010, the Eyjafjoell volcano under the Eyjafjallajokull glacier, further to the south, shot a massive plume of volcanic debris up to nine kilometres (six miles) into the sky, blowing ash across to mainland Europe.

The ash cloud caused the planet's biggest airspace shutdown since World War II, with fears it could damage aircraft engines.

The eruption caused global travel chaos, stranding more than eight million travellers as volcanic ash spread across Europe.

In 2011, Iceland's most active sub-glacial volcano Grimsvotn erupted, forcing Iceland to temporarily shut its airspace amid fears of a repeat of the Eyjafjoell flight chaos. http://news.yahoo.com/iceland-volcano-struck-biggest-earthquake-yet-stil... Video- http://news.yahoo.com/iceland-volcano-begins-erupting-sparking-red-alert...

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