After lying dormant for 4,000 years, one of Europe’s most powerful volcanoes, Campi Flegrei near Naples, is showing signs of life.
Instinct would tell you to stay away, but an international team of scientists are doing exactly the opposite. They are preparing to drill a 4km hole into the heart of the volcano to investigate beneath the surface.
Their aim is to pinpoint the source of mounting pressure that has caused the ground at the port of nearby Pozzuoli to rise dramatically over the past 40 years. Identifying the cause would help scientists to predict how close the volcano is to blowing.
“The volcano is breathing and there is a very serious seismic risk,” said Dr Ulrich Harms, a vulcanologist at the German Centre for Geoscience in Potsdam. A powerful eruption would cause widespread devastation and could cover thousands of square kilometres in volcanic ash, he said.
Locals may be alarmed by the venture, but leaders of the €8 million (£7.2 million) project, which is funded by the International Continental Scientific Drilling Program, claim there is no real risk of setting off an eruption.
“We’re not going to drill into the magma chamber or erupt the volcano,” said Dr Chris Kilburn, of University College London, one of the lead scientists. “We’re going to be standing on the damned thing so unless we want to commit some sort of collective euthanasia that wouldn’t be a good idea.”
He said that while the drilling would be deep — about 4km (2.5 miles) — geophysical surveys of the area suggested that there was no liquid magma closer to the surface than 8km (5 miles).
Even if they were unlucky enough to hit lava, the cavity of the borehole would be filled with the drill, meaning that there would be little difference in pressure between the puncture and the surrounding rock. The treacly consistency of magma would also prevent it surging through the borehole, which will be less than 1m wide.
“The idea that all the magma would come whooshing up the hole is total Hollywood fantasy,” said Dr Kilburn. “It would be like trying to suck porridge through a straw.”
In June, the Iceland Deep Drilling Project, a similar venture designed to tap geothermal energy from hot groundwater, hit magma without any explosive consequences. The only sign that the drill had hit a seam, more than 2km down, was a sudden drop in the resistance to drilling.
Despite the relative lack of risk, the project leaders expect locals to be concerned. “People in the area aren’t really aware of the project yet, but they are pretty volatile and there will be people upset about it,” he said.
Unlike conventional cone-shaped volcanoes, the Campi Flegrei has the form of a huge cauldron-shaped hollow, known as a caldera, caused by the collapse of land following a massive eruption 39,000 years ago. Smaller eruptions at sites close to the main caldera, which lies partly underwater, have left the land pitted with large moon-like craters.
Drilling towards the centre of the caldera could reveal the source of the upward pressure on Pozzuoli as well as allowing the locations of fractures and magma seams to be identified. One theory is that volcanic gases rising from below the magma chamber are heating up ground water, causing porous rocks beneath the surface to expand.
A more worrying alternative is that liquid magma has been pushed upwards and spread out in horizontal sheets beneath the surface. The drilling, which is set to start early next year, should be able to identify which of the two is taking place.
A secondary aim of the project is to assess whether the heat from the magma chamber could be harvested for geothermal energy. Liquid magma can be over 1000C and ground water at 3km deep is likely to be around 500C.