Domenico Patane of the National Institute on Geophysics and Volcanology in Catania, Italy, and his colleagues analyzed data on 647 earthquakes that occurred near Mt. Etna between 1994 and 2001. In a paper published online last week by the journal Science, the team argues that during that period, a huge volume of magma intruded below the volcano at the intersection of two fault lines. According to the report, the magma was initially confined to between six and 15 kilometers below sea level, but compression of the chamber combined with the magma's increasing volume forced it up to shallower depths. The escalating pressure within the mountain's plumbing system has fractured the rock and led to the most recent eruptions.
The blasts that began in 2001 differ from Etna's other blasts of the last 30 years. The scientists point out that older eruptions were typically followed by periods of very low seismic activity that could last for periods between a few months and two years. But after the 2001 outburst, seismic activity remained high. They conclude that "Mt. Etna eruptive activity could become more frequent, voluminous and potentially hazardous in the near future."