Scientists from Italy and France say that Vesuvius, the Italian volcano that transformed the Roman cities of Pompeii, Herculaneum and Stabiae into graveyards in 79 AD shows signs of doing the same soon.
Contrary to what most people believe, a volcano is not just the conic mountain that spits lava and ash towards the skies. In fact, this is just one of the many forms of a volcano. The general term describes any place where material(s) from the deeper parts of the planet reaches the surface.
Vesuvius is the only active volcano on the European continent and it has erupted around 35 times since the Pompeian disaster. Its latest eruption has been recorded in 1944, when 26 people died. In time, it has also been noted to give several warnings, such as poisonous hot gas, bursts of dust and ash clouds or even a bunch of slow flows of lava.
That's why in December 2004 Italian authorities offered 30.000 Euros (some $40,000) to the families closest to the mountain that wished to relocate. The 4 square mile (6.5 km)-radius region between the sea and Vesuvius is home to 500.000 people in 18 villages. Campania, the area that includes Naples, has invested 30 million Euros ($40 million) in hazard risk programs related to the volcano, in order to avoid the hugest peace time evacuation if the volcano ever explodes.
Which may happen sooner than expected. The current reports of the French-Italian team indicate that over the last 20.000 years the magma chamber beneath the surface of the volcano has been rising steadily. A magma chamber is a place underneath the planet’s surface where magma, rising from the deep, lacks enough pressure to push forward towards the surface and agglomerates. The shallowest of the reservoirs currently lies at depths comprised between 5 and 5.5 miles (8-9 km). The scientists explain that the depth where magma is found gives clues on its chemical composition and on the way it will release its energy.
As lead researcher Bruno Scaillet from the Institute of Earth Sciences in Orleans, France says, it is extremely important that the chemical composition of the magma is studied, because "If this magma is of a more acid composition, a type similar to the one which caused the Pompei eruption, you can expect an extremely explosive, dangerous eruption," he adds. That would endanger about 700.000 people. "On the other hand, if the magma is of mainly basalt composition, as in the last eruption in 1944, it would be of a flow type, with streams of lava, and that would be far less destructive," the scientist stated.
According to the researchers, the geological signatures indicate that from 20.000 years ago to the Pompeii catastrophe, the magma type of the volcano led to violent explosions and suffocating clouds of gas and dust. But, like in the current case of Stromboli, another Italian volcano, calmer lava flows have followed in the period between 1631 and 1944.
But Scaillet warns: "Just because there has been this trend for 2,000 years doesn't mean we can rule out a return to more acid magma. And because there hasn't been an eruption since 1944 doesn't mean we can say there won't be any more." The researchers associate the total silence in the last 64 years with 2 possible reasons: either magma slowly fills the magma chamber or the ceiling of the chamber has been sealed in time, which could lead to a disastrous explosion, should it be breached.
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