A sprawling volcano in Italy is at risk of an eruption for the first time since 1538, a study found. The Campi Flegrei (Phlegraean Fields) volcano may be less well-known than Vesuvius, but is “extremely dangerous”, study co-author Stefano Carlino told news agency AFP. With this, half a million people living on it are at risk as the conditions for an eruption have never been greater, the study said. Five hundred thousand people live in the red zone designated by Italy’s civil protection agency. Another 800,000 people live in the yellow zone.
Almost two millennia ago, Vesuvius wiped Pompeii off the map while the vast volcanic Campi Flegrei area near Naples last spewed lava, ashes, and rocks in 1538. However, the Campi Flegrei’s eruption 30,000 years ago is said to have led to the extinction of Neanderthal man.
The volcano can seem less dangerous than it is as it has the shape of a gentle depression 7.5-8.5 miles (12-14km) across, instead of growing into a traditional mountain. A resurgence of activity in the early 1980s led to the evacuation of 40,000 inhabitants, but the volcano has been relatively quiet since then.
“We’re not saying there will be an eruption, we are saying that the conditions for an eruption are more favourable,” Christopher Kilburn from University College London told AFP.
The tens of thousands of small earthquakes have taken place since the 1950s and have weakened the caldera, the basin at the top of the volcano.
The report – published in Nature’s Communications Earth & Environment journal on Friday – stated that “parts of the volcano had been stretched nearly to breaking point”.
“An eventual eruption could be preceded by relatively weak signals, such as a smaller rate of ground uplift and fewer earthquakes,” the study’s authors said, as per AFP.
They point to the eruption of the Rabaul caldera in Papua New Guinea in 1994, which was preceded by small earthquakes occurring at a 10th of the rate than those that occurred during a crisis a decade before.
The probability of a big eruption occurring is “very low”, Carlino said. “What is more likely are small eruptions,” he added, as per AFP.
Kilburn also said that the volcano being closer to rupture, does not necessarily mean that an eruption will take place. Even if the crust cracks, “the magma needs to be pushing up at the right location for the eruption to occur”, he said, as quoted by AFP.
The researchers used a model based on the physics of how rocks break and applied it in real-time to the volcano which is flat and mostly hidden either under buildings or coastal waters.
The model showed the tremors and ground movements and the researchers compared them with previous eruptions of other similar volcanoes.
“We cannot say with certainty what will happen, what matters is being prepared for any eventuality,” Carlino said, as per AFP.
Meanwhile, authorities have come up with an evacuation plan wherein residents will be moved out using their own or public transport within three days. The risk level – green, yellow, orange, and red – is reviewed monthly.
“The alert level in Pozzuoli is currently yellow,” council spokesperson Giordana Mobilio told AFP, further mentioning that locals receive alerts for all tremors of a magnitude of 1.5 or greater.