The Bay of Naples. Campi Flegrei can be found beneath the northern-central section of this image, and Vesuvius can be spotted to the east. NASA/JPL

The level of ground deformation at present, which is indubitably worrying, has been eclipsed in the past, however, to no consequence. Between 1982 and 1984, the ground rose by 1.8 meters (5.9 feet), a rate roughly 24 times that which is currently being observed – and yet, nothing disastrous happened. The current level of unrest, then, may be another red herring.

Nevertheless, the scientific concern over Campi Flegrei is far from hyperbolic. Kilburn told IFLScience that the unrest at the volcano from 1950 onwards is the “first sign of uplift at the caldera for four centuries,” noting that the last time this pattern was observed, Campi Flegrei erupted, in 1538.

“Please note, though, that an eruption is not guaranteed – it’s just more likely than during previous episodes of uplift,” he said.

The 1538 eruption, by the way, was peanuts compared to its formation 40,000 years ago, which was easily one of the most powerful in the last few million years. This blast produced between 100 and 500 cubic kilometers (20 to 120 cubic miles) of volcanic debris, some of which made it all the way up to Greenland.

“At present, there are residents who have been through two emergencies without eruption, so it is natural for them to be skeptical,” Kilburn said. “However, the lack of eruption until now is no reason to believe this will always be the case.”

IFLScience and WIRED, through different means, both came to the conclusion that this particular caldera is the most dangerous volcano in the world, by far – something that few volcanologists would disagree with.

At least 1 million live within its crater, and up to 6 million live within the “blast zone.” There is definitely an active magma chamber beneath the surface, and unlike Yellowstone – a far more famous “supervolcano” – it is showing signs of unrest. This latest study adds another worrying facet to its potential future ferocity.

Buona fortuna, everyone.