VESUVIUS is sinking, making the kind of eruption that buried Pompeii in AD 79 less likely, according to Andrea Borgia from the European Development and Research Agency in Rome, and his colleagues.
The slumbering volcano, which last erupted in 1944, sits on a layer of sediment. 鈥淭he volcano is sinking into the sediments,鈥� says Borgia. Satellite radar measurements of the volcano鈥檚 height show the central cone is sinking at a rate of 1 to 2 millimetres per year, while an arc-shaped ridge is rising up at the foot of the slopes. Borgia says these features, and fissures that have appeared in the flanks, are caused by the sides of the volcano spreading out (Geophysical Research Letters, vol 32, p L03303).
He argues that gas from the magma beneath will escape through the cracked sides, lessening the risk of an explosive eruption. Instead, rivers of lava may flow down the slopes. 鈥淭hey will be very destructive as well, but maybe people will be able to run away,鈥� Borgia says.
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But Bill McGuire, a volcanologist with the Benfield Hazard Research Centre in London, is not convinced that the features Borgia鈥檚 team has seen affect the volcano鈥檚 danger levels. 鈥淚 would certainly not want to see any modification of the current assessment of volcanic risk,鈥� he says.
