Massive magma layer feeds Vesuvius

The last major eruption was in 1944
Image: Paolo Gasparini

		By BBC News Online's Ivan Noble

Italian and French researchers have discovered a massive layer of magma eight kilometres (five miles) below Mount Vesuvius, the Italian volcano which last underwent a major eruption in 1944.

The layer is much bigger than they expected and appears to stretch beneath Vesuvius and neighbouring volcanoes such as the Phlegraean Fields close to Naples itself.

Paolo Gasparini of the University of Naples Federico II told BBC News Online that he and his colleagues had taken a snapshot of the situation under the mountain.

The snapshot does not provide any indication of what will happen beneath Vesuvius in the future, but it does point to a zone which should be monitored for seismic clues.

Seismic survey

"There is a huge amount of available magma under Vesuvius," he said.

"It was really unexpected for the reservoir to be that size."

Dr Gasparini is part of a European team which carried out surveys of the rock beneath Vesuvius in 1996 and 1997.

"We collected a huge amount of data. There has been very extensive work processing the data and interpreting it," he said.

The team detonated several tonnes of explosives in over a dozen locations around the mountain and measured the shock waves from the explosions after they passed beneath the volcano.

They also let off hundreds of shots from guns aboard a ship in the Bay of Naples.

The layer they found beneath Vesuvius stretches across 400 square kilometres (154 square miles), but they were unable to tell how thick it is.

But they are now carrying out more surveys to find out exactly how far it stretches beneath other volcanoes.

The research is published in the journal Science.