- More than 500,000 people live within the "red zone" of the volcano.
- The hope is that 150,000 people will be lured by the incentives and move out.
- If Vesuvius exploded it would result in one of the biggest peace-time evacuations.
Italian authorities have renewed the cash offer of up to 30,000 euros (about $40,000) for any family wishing to move outside the shadow of Mount Vesuvius in the attempt to reduce the potential hazard of what has been described as the world's most dangerous volcano.
Campania, the region that includes Naples, last month set up a 30 million euro ($40 million) Vesuvius hazard risk program, confirming and improving last year's cash offer for those wishing to relocate to safer areas.
The aim is to thin out the number of people living in the dangerous "red zone," thus reducing the time for what would be one of the biggest peace-time evacuations, if Vesuvius exploded.
At present, more than 500,000 people live in the zone, an area comprising 18 villages squashed within a four-mile radius between the volcano and the sea.
The only active volcano on European mainland, Vesuvius has erupted about three dozen times since 79 A.D., when it buried Pompeii and the nearby towns of Herculaneum and Stabiae.
The volcano hasn't blown its top since 1944. At that time, lava destroyed some orchards and homes and 26 people were killed.
Even though there is no warning sign of an imminent eruption, the effort of regional authorities to lure people out of the danger zone indicates that the threat is not underestimated.
"The next eruption could occur within some decades or some hundreds of years. Most likely, it will be an explosive one," the Vesuvian Observatory said in a statement.
According to vulcanologists' reports at the latest World Geological Conference in Florence, the next event will probably resemble the 1631 eruption.
The lava flow from that eruption killed about 3,000 people, making it the worst since 79 A.D.
With such an explosive eruption, people living in an area of 15 kilometers (nine miles) from the volcano will have little hope of survival, according to the first physically based hazard estimates from pyroclastic flows in the Vesuvian area.
"Our simulations show that pyroclastic currents similar to those produced in the 79 A.D. eruption can reach even larger distances. Not to mention the thermal effects," Giuseppe Mastrolorenzo, who led the study with Sergio Rossano of the Osservatorio Vesuviano and colleagues from Naples University, told Discovery News.
"We established that the temperature in Herculaneum, which is about seven kilometers (four miles) from the volcano, was above 500° Celsius. The temperature remains high even at bigger distance," he said.
Under such conditions, lahars — volcanic mudflows — will follow, reaching an area of more than 20 kilometers (12.5 miles) from the volcano, Mastrolorenzo said.
In this catastrophic scenario, the pool of possible Vesuvius victims will increase because of the panic.
"Our only choice is to reduce the number of people living in the danger zone. The region's new cash offer contains new rules to make it possible for all those who did not have the requirements under the previous regulation to obtain the incentives," said Marco Di Lello, urban planning counsellor for the Campania Region.
He added that 3,276 families applied under the previous scheme. The hope is that within 10 years about 150,000 people will be lured by the incentives and move out.
Monitoring the gases emitted by lava and their isotope content could be a useful tool for predicting what kind of an eruption there will be, according to a recent study by Jon Blundy from the Earth Sciences Department at Bristol University in England.
In his research, Blundy demonstrated that rocks that erupted in 1980 from Mount St. Helens, in Washington, preserve a remarkable record of the goings-on beneath the volcano in the period prior to its eruption.
Blundy and his team showed that the magma that erupted explosively at that time came largely from two reservoirs — a deep one and a shallow one — while subsequent, more gentle eruptions came exclusively from magma trapped at shallow levels.
"We have shown that there is a link between the storage depth of magma and the explosiveness of an eruption. I think this monitoring can be also applied to Vesuvius. If it is coupled with more traditional techniques, then I think that there is great potential," Blundy said.