Active volcanoes produce a mix of seismic signals or small earthquakes that can indicate an eruption, but interpreting their significance is notoriously difficult.

So the capacity to analyse these signals under laboratory conditions and understand how they are caused by water, steam, gas or magma rushing through cracks in rock is a significant step forward.

Philip Benson of University College London and colleagues reported their findings in the journal Science on Thursday.

They reproduced the stresses found inside a volcano by forcing water through drilled cylinders of basalt, at pressures typically found 2.5 km (1.6 miles) underground, and then released it suddenly.

"We can better forecast eruptions and the different cycles of eruptions with better time accuracy as we understand more about the physical mechanisms that go on," Benson told Reuters.

Luigi Burlini of the Institute of Geology in Zurich and Giulio Di Toro of Italy's University of Padua said such experiments made it possible to study stress mechanisms separately -- effectively allowing scientists to identify different "instruments" in the seismic "orchestra".

"This understanding should allow for better predictions of the intensity and timing of volcanic eruptions, so that early warning and alerts can save lives," they wrote in a commentary in Science.

Separate research on the Soufriere Hills volcano on the Caribbean island of Montserrat, which has been erupting since 1995, suggests volcanoes are in fact even more complex than expected.

Rather than "ballooning" at depth, as previously thought, pressurised magma was found to recharge the volcano repeatedly, causing episodic eruptions, an Anglo-American team of scientists reported in the same journal. (Editing by Charles Dick)