About 30 meters to my right, steam rose into the sky in thick grey-white clouds. And somewhere between where I stood now, and there, the earth turned from solid and cool to boiling and viscous. Wherever that exact change happened, I wanted to make sure I wasn’t too close. “It’s very dangerous here,” said volcanologist Enzo Morra, my guide for the day. He was already climbing the hill on the other side of the wooden slats before me.
As I edged one foot onto one piece of wood, then the next, the ground felt firm. As I reached the far side and climbed the hilltop, I could see the source of the steam: a bubbling pool of dull gunmetal-grey mud, ominous as the contents of a witch’s cauldron and a great deal louder. The air smelled of sulphur.
“It’s very dangerous here,” Morra welcomed me when I arrived. “More dangerous than Vesuvius.” Campi Flegrei is one of 20 known “supervolcanoes” on the planet. I laughed nervously. “I wish you’d told me that when we were over there. Why are you telling me that when we’re here?”
We were overlooking one of the fumaroles of Campi Flegrei, known in English as the Phlegraean Fields. One of 20 known “supervolcanoes” on the planet – capable of erupting with a volume thousands of times stronger than an average volcano – Campi Flegrei commands less notoriety than Mt Vesuvius, just 30km to the west.
But that is largely due to luck. If Campi Flegrei were to blow at maximum capacity today, it would make the 79AD eruption of Mt Vesuvius that destroyed Pompeii look like a puppy’s sneeze. Fortunately, Campi Flegrei hasn’t had a full-force eruption in thousands of years.
That isn’t to say it’s impossible. Researchers call the supervolcano “restless”, and there are concerns it is becoming more so. In 2012, the alert level was raised from green to yellow, indicating a need for more monitoring. Most recently, a “seismic swarm” in April 2020 saw 34 different earthquakes.
Campi Flegrei is more than a (fitfully) snoozing menace. It’s why the ancient Romans built one of the most magnificent resort towns on the Italian peninsula here: Baiae, famed for its hot springs and bad behavior. It’s also why at least half of the town, with its precious marbles, mosaics, and sculptures, sank beneath the Mediterranean over the following centuries. Now, this “restless” supervolcano is the reason why much of this archaeological site is at risk today – both in…
