Effects of Katla eruption would put current air travel chaos in the shade

 

OTHER VOLCANOES:SHOULD THE Icelandic volcano Katla erupt the resulting spread of ash from the eruption column could disrupt air travel in Europe for several weeks.

The disruption to air travel caused by the current eruption in Eyjafjallajökull would pale in comparison with such an eruption, assuming that it was of the same magnitude as the infamous Katla eruption of 1918.

“Such an event could form an eruption column stretching up to 20km into the stratosphere,” Haraldur Sigurðsson, a world authority on volcanoes, said.

“The distribution of ash could greatly exceed the spread from the current eruption column at Eyjafjallajökull, which has stretched 6-10km in the troposphere, and reach a substantially greater portion of the European continent.

“The flow of magma or molten rock from Katla in 1918 was 10 times greater than the current eruption, although there is no guarantee that the next Katla eruption would be of the same magnitude.”

Prof Sigurðsson said the spewing of ash from Eyjafjallajökull was caused by the explosive nature of the gas-rich andesite magma that is erupting.

Icelandic settlement reaches back to the late 9th century AD, with three documented instances of an eruption in the Eyjafjallajökull volcano preceding an eruption in Katla, but 22 documented eruptions in the much more active Katla in the same period.

This connection has not been lost by geologists observing the disaster.

According to Prof Sigurðsson, these eruptions, in AD 920 (estimate), 1612 and 1823, are too few to establish a demonstratable pattern, suggesting that history may not repeat itself this time around.

Nevertheless, a scenario in which the current eruption triggers Katla to erupt is quite possible, as Helgi Björnsson, one of Iceland’s foremost glacier experts, points out with a reference to the interconnectivity of the volcanic system and historical records.

An eruption in Katla would not only inflict economic losses upon Europe, as the impact of the eruption and resulting flooding could greatly exceed the damages by the Eyjafjallajökull eruption in the area.

Icelandic history is rich of tales of the might of the much-feared Katla volcano.

Photographs taken of the 1918 eruption provide the first visual account of the extraordinary forces at play.

The magnificent eruption column aside, the photographs show how icebergs carried by the flooding from the 600-metre or so deep ice shield over the Katla crater could reach up to 30 metres in height, according to Porir Kjartansson, a history enthusiast who recalls tales from the area.

For comparison, the ice sheet on Eyjafjallajökull is estimated to be 250 metres thick.

Mr Kjartansson says that the flooding is also considered to have brought a 2,000-ton rock from the volcano to the black volcanic desert of Mýrdalssandur, while also extending the beach by a factor of 2km within the first 24 hours of the 1918 eruption.

Mr Björnsson adds that locals feared eruptions and resulting flooding in the nearby desert to the extent that they created emergency plans should the bursting floods begin while they were crossing the volcanic sands.

Porour Tómasson, curator at the Skógar Museum near the volcanic desert, also recalls tales of dramatic destruction of farms and livestock in floodings from the volcano.

One of these tales describes how adjacent pasture and farmhouses were covered so extensively by the ferocious flooding that only a single horse standing on a hill escaped.

Mr Björnsson also recalls a dramatic tale from 1311 in which a man and an infant survived a flood caused by Katla by staying on the surface of an iceberg that the tide would later bring back to the beach. They were the only ones to survive.