REYKJAVIK: Iceland raised its alert over the nation’s largest volcanic system to red on Saturday, banning all air traffic in the area, after detecting a small sub-glacial eruption.

A major explosion at the Bardarbunga volcano could signal a replay of the global travel chaos triggered when another Icelandic peak blew four years ago, creating a massive ash cloud across Europe.

“There is an ongoing eruption beneath the glacial surface, probably a small eruption which has not been enough to melt the ice cap,” Iceland Met Office official Theodor Hervasson said.

Police said a number of tourists were being evacuated in an area located north of the Bardarbunga volcano, which lies in southeast Iceland.

The authorities said they had decided not to evacuate residents of nearby areas, but encouraged them to be alert and have their mobile phones switched on at all times.

Iceland had raised its aviation alert to orange on Monday after Bardarbunga kicked into seismic action with the biggest earthquake registered since 1996.

However police said on Saturday that there was no sign of a change at the surface of the erupting area and that the ice layer was between 150 and 400 metres thick.

“The eruption is considered a minor event at this point,” the national police commission said in a statement.

“Because of pressure from the glacier cap it is uncertain whether the eruption will stay sub-glacial or not,” the statement said.

There are fears that a major eruption would melt the glaciar but police said that for the moment there was no indication of a flooding risk. The eruption of Eyjafjoell, a smaller volcano, in April 2010 caused travel mayhem, stranding more than eight million travellers in the biggest airspace shut down since World War II.

“There’s nothing we can do if we get another big eruption like that of Eyjafjoell except to interrupt air traffic in the dangerous areas,” Icelandic Civil Aviation Administration spokesman Fridthor Eydal was quoted as saying earlier this week. “It’s really the only thing we can do,” he said.

Bardarbunga lies under the country’s largest glacier Vatnajoekull. The area around it is uninhabited, with only trekking cabins and campsites used by tourists and hunters in the summer months.

It is Iceland’s second-highest peak, rising to more than 2,000 metres, and caps the country’s largest volcanic system.

On Monday, seismologists recorded an earthquake of 4.5 on the Richter scale in the area.

Scientists believe its explosion would be large enough to disrupt air traffic over northern Europe and the northern Atlantic, as well as causing major damage on the island nation from volcanic ash and glacial flooding.

In 2010, the Eyjafjoell volcano in the south of the island shot a massive plume of volcanic debris up to nine kilometres (six miles) into the sky, blowing ash across to mainland Europe. And in 2011, Iceland’s most active sub-glacial volcano Grimsvotn erupted, forcing Iceland to temporarily shut its airspace and sparking fears of a repeat of the Eyjafjoell flight chaos.

Iceland is home to more than 100 volcanic mountains, some of which are among the most active in the world.

Published in Dawn, August 24th, 2014