July 7, 2011

Is There A New Volcanic Eruption In Iceland’s Future?

One of Iceland's most active and most feared volcanoes looks like is getting ready to erupt, with measurements indicating magma movement, according to Icelandic experts on Wednesday, raising fears of a new ash cloud disrupting air traffic in Europe and abroad.

The Hekla volcano, dubbed by Icelanders in the Middle Ages as the "Gateway to Hell," has erupted some 20 times over the past 1000 years, with the most recent eruption occurring on February 26, 2000.

Hekla is close to the ash-spewing Eyjafjallajokull, which erupted last year causing the biggest closure of airspace since World War II, affecting more than 100,000 flights and 8 million travelers.

The Iceland Civil Protection Authority said it was closely monitoring the volcano.

"The movements around Hekla have been unusual in the last two to three days," University of Iceland geophysicist Pall Einarsson told the AFP news agency. While the events do not necessarily mean there will be an immediate eruption, "the volcano is ready to erupt," he stressed.

"The mountain has been slowly expanding in the last few years because of magma buildup," Einarsson added.

Geophysicist Ari Trausit Gudmundsson, said the measurements around Hekla were very "unusual" and that the volcano looked ready to blow. "Something is going on," he told the French news agency, though it remains unclear when it will blow.

Hekla has erupted about once a decade over the past 50 years. It eruptions are varied and hard to predict. Some have lasted just a few days, while others have gone on for months or years.

Measuring 4,892 feet and located about 70 miles east of Reykjavik, Hekla is so active that scientists estimate about 10 percent of the tephra -- solid matter ejected when a volcano erupts -- produced in Iceland over the past 1000 years, comes from this one volcano.

Gudmundsson, answering a question as to what kind of disruptions could be expected if and when Hekla erupts, said the volcano tends to "produce both ash and lava within the first seconds of an eruption."

Lava eruptions are far less disruptive to air travel, and "if the next eruption is of the same character (as the previous ones) it is unlikely" that it will affect flights in Europe, he said.

But this also "depends on the size of the eruption, which is something that is impossible to predict," he added.

"Hekla never gives you much of a warning," Einarsson told AFP, pointing out that in 2000, it began rumbling 90 minutes before the outbreak of magma, which "was actually an unusually long warning. In 1970 we only got 25 minutes notice."

Rongvaldur Olafsson, a project manager at the Icelandic Civil Protection Authority, told The Telegraph that no immediate safety precautions were being taken but: "We will watch the mountain and developments very closely."

Hekla's first recorded eruption, in 874, produced 2.5 cubic kilometers of tephra. That number is four times as much as the 0.6 cubic km produced by Iceland's Grimsvotn volcano in May, which caused flights to be cancelled across northern parts of Britain.

Eyjafjallajokull's April 2010 eruption produced about 1.8 cubic km over a three day period. The main reason it grounded so many flights for over a week was that the ash cloud hung so low.

Hekla has the potential to be even more severe. How bad it could be depends on the scale of the explosion and the speed and direction of prevailing winds.

Eruptions have occurred in 874, 1158, 1206, 1222, 1300, 1341, 1389, 1510, 1597, 1636, 1693, 1766, 1845, 1947, 1970, 1980, 1991 and 2000.

The eruptions in 1510, 1693 and 1766 caused the most damage.


Image Caption: Steam at the summit of Hekla. Credit: Borkur Sigurbjornsson/Wikipedia (CC BY 2.0)