Volcanoes function in a far more complex way than previously thought, making future eruptions even harder to predict, a new research by a team of US and British scientists into volcanoes has found.

The findings by scientists at the University of East Anglia in Britain and Penn State University and the University of Arkansas in the United States will appear on the October 10 issue of journal Science.

The main discovery is that rather than "ballooning" at depth, as previously thought, the pressurized magma in fact recharges the volcano repeatedly, causing episodic eruptions at the surface.

The research was conducted on the Caribbean island of Montserrat, a British territory on which the Soufriere Hills Volcano has been erupting since 1995.

Its eruption has caused widespread damage to the island and its infrastructure, resulting in the displacement of so many people that the island's population has reduced from 13,000 to only 4,500. In 1997, avalanches of hot rocks, known as pyroclastic flows, destroyed the capital town of Plymouth and the island's airport, claiming more than 20 lives.

The team measured the surface flux of lava through detailed topographic surveys of the lava dome and deposits, as well as the response of the ground surface around the volcano using GPS to assess the amount of inflation or deflation in response to magma movement.

The scientists have developed a physical model to reconcile these measurements and provide a picture of how magma moves from the mid-crust to the surface.

"Our findings show volcanic eruptions to be even more complex than we had originally believed and illustrate the urgent need for further research into this and other volcanoes," said the authors.

(Xinhua News Agency October 10, 2008)