Volcanoes' plumbing holds clues to eruptions

The secret to predicting a volcano's eruptions may lie in its plumbing.

New research looking at volcanoes in Iceland and the Afar region of Ethiopia ? the two areas where mid-ocean ridges, where Earth's tectonic plates are moving apart, are visible at the surface of the Earth ? found that the underground caverns holding a volcano's magma aren?t buried as deeply as scientists had thought. These caverns, called magma chambers, also swell, shrink and pulse every now and then, yielding possible clues about the size and timing of a volcano's next big eruption.

"The study shows that the deep magmatic plumbing of each volcanic segment, as well as the numbers of individual magma chambers and their connections, is more complicated than we expected," said Carolina Pagli, a geologist at the University of Leeds in England. Pagli led one of two studies on spreading-center volcanoes published this month in the journal Nature Geoscience.

The majority of Earth's volcanoes are located at spreading centers, which form a 37,000-mile-long (60,000 kilometers) network, splitting the Earth into its major tectonic plates. Most of these spreading centers are underwater, which makes detailed observations very difficult. But the spreading centers exposed in Ethiopia and Iceland offer a rare glimpse into the inner plumbing of the Earth.

Mapping magma chambers and figuring out how they behave can help identify early warning signs hours ? or even months ? before an eruption.

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For example, the ground started uplifting (elevating) four months before a 2008 eruption in Ethiopia, because an influx of new magma increased pressure in an underground chamber. An increase in earthquake activity was another signal, Pagli said.

The researchers found that separate magma chambers can feed a single eruption, and those chambers can be oriented both horizontally and vertically, allowing magma to spew in multiple directions. They also found that the magma chambers feeding the 2008 Ethiopia eruption lie only half a mile (1 km) below ground. Earlier models had assumed those chambers were more than 2 miles (3 km) deep.

The 2010 Eyjafjallajokull eruption in Iceland is an example of a successful forecast using these signals, Pagli said. Researchers monitoring the volcano detected precursory swelling and changes in earthquake patterns, and they were able to coordinate with officials to evacuate high-risk areas.

"Examples from Iceland teach us that a successful forecast is based on longtime series of observations and an effective monitoring network," Pagli told OurAmazingPlanet. "European countries should invest in the knowledge that arises from the events in Iceland and Afar to better understand how volcanoes work."

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