Eighteen months ago I was in the Earth's other potential supervolcano, Campi Flegrei ("fiery fields") in Campania, Italy. Vesuvius is close by but isn't really part of the Campi Flegrei, which is represented today by a huge caldera which is largely underwater off Pozzuoli. There is a huge magma chamber not far under the surface, and it causes slow heaving and falling of large areas of ground ( bradiseism) as it swells and retreats. In the early 1980s the town of Pozzuoli was largely evacuated after the ground rose by about eight feet in a very short time (it was a false alarm). We went into the crater of La Solfatara, just outside Pozzuoli, which last erupted a thousand years ago. There are lots of fumaroles and several boiling mud pools and the ground in one place melted my sandals. The last serious action in the Campi Flegrei was about five hundred years ago when a new volcano suddenly appeared (Monte Nuovo). About 37000 years ago there was a massive eruption of the Campi Phlegraean volcano which covered thousands of square miles around the Bay of Naples and the Sorrentine peninsula with ash, and this eruption may have resulted in the final demise of Neanderthal Man.

Campi Flegrei was one source of the legend of the Elysian Fields, such was its beauty, but, sadly, these days it's largely covered by drab suburbia. The area, which includes Naples, has a population of about three million, all vulnerable to any future supervolcano eruption. Add the menace of Vesuvio to that, and you have what could well be the most dangerous place in the world to live in. But it's marvellous, and the Bay of Naples and the Amalfi Coast are the loves of my life. The non-human ones at any rate.