Sliding Volcano

Europe's most active volcano, Mount Etna, is sliding towards the sea. Scientists have established that the whole structure on the Italian island of Sicily is edging in the direction of the Mediterranean at a rate of 14mm per year.

The UK-led team says the situation will need careful monitoring because it may lead to increased hazards at Etna in the future. "I would say there is currently no cause for alarm, but it is something we need to keep an eye on, especially to see if there is an acceleration in this motion," Dr John Murray told BBC News.

The Open University geologist has spent almost half a century studying Europe's premier volcano. In that time, he has placed a network of high-precision GPS stations around the mountain to monitor its behaviour. This instrumentation is sensitive to millimetric changes in the shape of the volcanic cone; and with 11 years of data it is now obvious that the mountain is moving in an east-south-east direction.

Essentially, Etna is sliding down a very gentle slope of 1-3 degrees. This is possible because it is sitting on an underlying platform of weak, pliable sediments. Dr Murray's team has conducted lab experiments to illustrate how this works. The group believes it is the first time that basement sliding of an entire active volcano has been directly observed. Dr Murray and colleagues stress such behaviour is very rare and can take many centuries, even thousands of years, to develop to a critical stage.

Certainly, there is absolutely no evidence that this is about to happen at Etna. Local residents should not be alarmed, the Open University scientist said.