Mount Etna is sliding towards the sea

Mount Etna is Europe's most active volcano, but it harbours an unexpected danger. Scientists have recently established that the whole structure on the Italian island of Sicily is edging in the direction of the Mediterranean at a rate of on average 14 millimeters per year. The volcano is sliding down a very gentle slope of 1-3 degrees[1]. This is possible because it is sitting on an underlying platform of weak, pliable sediments.

Lead author Dr John Murray and his team have placed a network of GPS stations around the mountain to monitor its behaviour. This instrumentation is so sensitive that it can detect millimetric changes in the shape of the volcanic cone. It has detected that the mountain is moving in an east-south-easterly direction, on a general track towards the coastal town of Giarre, which is about 15 kilometers away. At the current rate of speed, it will take Mount Etna roughly 100 million years to reach Giarre.

14 millimeters per year may seem small, that is 14 meters per century, but geological investigations elsewhere in the world have shown that extinct volcanoes that display this kind of trend can suffer catastrophic failures on their leading flank as they drift downslope. Stresses can build up that lead eventually to devastating landslides.

"I would say there is currently no cause for alarm, unless there is an acceleration in this motion," Murray said. "The thing to watch I guess is if in ten years' time the rate of movement has doubled - that would be a warning. If it's halved, I'd say there really is nothing to worry about."

[1] Murray et al: Gravitational sliding of the Mt. Etna massif along a sloping basement in Bulletin of Volcanology - 2018