When the sleeping giants wake

Iceland’s 2010 volcanic eruption was merely an economic disaster; future eruptions may have more dire effects, which is why Irish scientists are trying to improve the accuracy of predictions

NEW ZEALAND’S Mount Tongariro blew its top last week, belching out enough ash to close roads and disrupt regional air travel. Yet who could have predicted the eruption, given that the volcano had been quiescent for the past 115 years?

European air traffic experienced much wider disruption in 2010 when Iceland’s Eyjafjallajökull underwent a major eruption lasting weeks. It, too, had been quiet for 90 years before it sprang to life.

Volcanologists have long sought to better predict the erratic behaviour of volcanoes. And Irish scientists this month travelled to Iceland in pursuit of this goal. Two of them hiked thousands of feet up the Hekla volcano, placing motion sensors close to its summit before returning home last weekend.

The scientists aim to figure out what is happening beneath a volcano and so improve the accuracy of forecasts. The sensors will record any earthquakes over the next two months.

“We are interested in the specific precursory signals that are sometimes seen before an eruption,” Christopher Bean, professor of geophysics at University College Dublin, explains. He was accompanied by his colleague Dr Aoife Braiden, with logistical support from the Icelandic Met Office.

Hekla, one of Europe’s most active volcanoes, is a likely candidate for Iceland’s next eruption. It has erupted dozens of times since the 12th century and its ash falls turn up in many Irish bogs.

Before an eruption, molten rock moves upwards and this can be detected in ground vibrations. Bean’s sensors – seismometers – measure these tremors and he uses computer models to work out whether they are due to magma, or gas movement or the volcano edifice itself creaking.

Bean compares it to a cardiograph: looking at individual wiggles and diagnosing what’s happening. “We want to understand what those signals are telling us,” he says. Precise predictions are not easy, however. “Even though you record the signals, it is like the straw that breaks the camel’s back.” The pressure caused by gas escaping from magma kilometres below the surface can have a large influence on eruptions.

The volcanic ash cloud from the 2010 Eyjafjallajökull eruption caused the cancellation of 100,000 flights, inflicted €4 billion in economic damage and, at its peak, closed 80 per cent of European airports. Iceland has about 30 active volcanos and there is evidence that they affected Ireland’s climate in past centuries (see panel). A handful of these volcanos remain under close scrutiny.