In the square in Monterusciello, a few kilometres from Pozzuoli, 12-year-old Angelo Di Roberto climbed into the civil defence bus with his grandfather. “None of my schoolmates wanted to come, but I wanted to” he said. “It seemed like the right thing to do.”
He was right. It was important. The authorities were simulating a large-scale evacuation, the kind they would have to carry out in the event of a volcanic eruption in the seismically active Campi Flegrei or Phlegraean Fields near the southern Italian city of Naples.
Everyone in the sprawling volcanic area hopes it will never happen, but the signs are ominous.
Since January 2024, the land in certain parts of the Phlegraean Fields has risen by about 20 centimetres (eight inches) as a result of a phenomenon called bradyseism, the gradual uplift or lowering of part of the Earth’s surface caused by the filling or emptying of an underground magma chamber or hydrothermal activity, particularly in volcanic calderas.
Earthquakes continue to be recorded almost every day. There were 6,066 in 2023 and as many as 6,740 in 2024. The seismic swarm continues in 2025, generating anxiety and fear that leads many people to spend nights in their cars or outdoors. The most violent earthquake to hit the area for four decades shook buildings in and around Naples earlier this month.
Every year 700,000 tourists climb the great cone of Vesuvius to admire one of the most beautiful gulfs in the world. But if you stretch your gaze westwards, beyond Fuorigrotta, you catch a glimpse of other small, almost completely unknown volcanoes: these are the Phlegraean Fields, an enormous caldera which is home to more than 600,000 people.
Just as many live around Vesuvius, a population density that makes the entire area one of the most dangerous on earth: a supervolcano which on average erupts every 50,000 years, events that are difficult to predict but have potentially disastrous consequences.
At the Pisciarelli fumaroles, Rosario Avino and Antonio Caradente, technicians from the national institute of geophysics and volcanology (INGV), arrive towards evening. The sun is setting, smoke is billowing from the fissures and the river of boiling mud takes on a reddish colour.
They check sensors placed to monitor Solfatara, a shallow volcanic crater at Pozzuoli, and before leaving they cast an eye inside an abandoned building. Here the walls are covered with yellowish sulphurous incrustations that are slowly but surely breaking through the walls and floor.
“Get out quickly because the carbon dioxide levels are very high and could be harmful,” Rosario shouts.
Solfatara, with its white rocks and perennial vapours, is an evocative place and a destination for tourists. But it is also fraught with danger. The area was closed in 2017 after a child and his parents fell into a cavity and died.
The true morphology of this crater-rich land can only really be grasped from above. A bird’s eye view reveals that those circles disguised as hills and covered with dwellings are, in fact, extinct volcanoes.
Bradyseism, literally “slow movement”, continues to raise the ground across the Phlegraean Fields. It raised Pozzuoli by two metres in the 1980s, leading to the evacuation of 40,000 people from the Rione Terra neighbourhood.
Bradyseism has always existed in these parts. On the Roman columns of the Temple of Serapis you can still see the holes made by stone-eroding organisms, created when the ground subsided about 10 metres in the following centuries. For a long time they were submerged in sea water.
“The ground keeps breaking and deforming,” Mauro Di Vito, the director of INGV’s Vesuvius observatory, explained. “And the accumulation of stress generates earthquakes. But this is an expected phenomenon and it is very likely that earthquakes will continue. We will all have to get used to reacting in a positive way, without panicking. We scientists cannot exclude anything. Our job is to monitor and measure the parameters.”
The Phlegraean Fields are among the most monitored volcanoes in the world, designed to detect the smallest sign of an awakening that will happen sooner or later. There is a contingency plan for a mass evacuation, but will it ever work? If the supervolcano really were to erupt, would it leave anyone behind?
What we do know is that past eruptions have made the land of the Gulf of Naples some of the most fertile in the world. Think of Vesuvian apricots, figs and cherries, the Piennolo tomato and native grape varieties such as Piedirosso and Falanghina. They have also generated thermal emissions that have been exploited for centuries and provided precious yellow ash stone known as tuff, with which Campania’s towns were built. This is maybe why, despite being one of the most dangerous lands in the world, the area between the Phlegraean Fields and Vesuvius is also one of the most populous.
Certainly, those who live in the area establish a visceral bond with the volcano built on fear and respect. To protect themselves from the risks, the inhabitants have always relied on a belief in divine benevolence, naming not only churches and festivals after local Madonnas and saints, but also rituals. One is dedicated to the melting of the blood of San Gennaro, which for centuries has been thought by some to ward off magma. The volcano has featured in art, poetry, popular song and everyday festive life. It has moulded the fatalistic character of those who live here, and who know that, at any moment, everything could end.
There are many problems in the area. There is unemployment, widespread crime, illegal waste disposal and reckless urban planning that fuels landslides and floods with devastating consequences.
Amid all this, the possibility of an eruption is secondary, and a recent survey revealed that for the population of the Phlegraean Fields the perception of risk is low.
Those who live in the Pozzuoli area forget that although they do not have a conical mountain looming over them, what they have under their feet is a time bomb. And no one really knows when it will explode.
