Two thousand years ago Mount Vesuvius destroyed Pompeii. Today, a larger, far more deadly supervolcano lurks on the other side of Naples. If it erupts, Campi Flegrei could wipe out all life in Europe. So why are British scientists battling the Italians for the right to poke at it with drilling rods?

The Campi Flegrei caldera is a supervolcano. While a new eruption here would be more likely to result in the creation of another Vesuvius-like cone, the worst-case scenario could see it obliterating much of life in Europe

NAPLES, ITALY, THE NEAR FUTURE

It begins with a swarm of 1,000 small earthquakes that ripple under the pavements of Naples. Air-conditioning units fall from the sides of buildings and tiles slip from the walls. Inside the National Institute of Geophysics and Volcanology’s control centre, a bank of screens indicates that the quakes aren’t being generated by the giant Mount Vesuvius, which looms over the city.

These quakes are coming from something far bigger, from one of the largest and most dangerous volcanoes in the world: the Campi Flegrei caldera. Vesuvius, which destroyed the Roman city of Pompeii, incinerating and suffocating thousands, is nothing more than a pimple on the back of the sleeping dragon of Campi Flegrei, an active four-mile-wide sunken volcano. A call is quickly put through to Civil Defence and the Italian Ministry of the Interior: the city must be evacuated immediately.

A short distance away, the ground around the ancient town of Pozzuoli is stretching, swelling, doming. Fumaroles – vents emitting columns of steam rich in CO2 – open up in the broken Tarmac. Four-and-a-half miles below the surface a bolt of magma has escaped the main reservoir and is rising upwards, changing and solidifying. As it reaches groundwater, it’s converted into a sponge-like stone. As the water boils away it feeds critical amounts of gas into the sponge, and the pressure builds until finally it explodes like a malfunctioning boiler.

Hundreds of billions of cubic feet of volcanic rock blasts up into the atmosphere: an explosion 200 times greater than that of the Icelandic Eyjafjallajökull volcano, which brought chaos to Europe, grounded planes in the UK for a week and is said to have cost the world economy in excess of £3 billion.

Back on the streets of Naples, it’s too late to run. Bumper-to-bumper traffic comes to a halt as drivers grind on their horns. They watch helplessly as a boiling black cloud of hot gas and rock rolls over the horizon at hurricane speed, suffocating everything in its path. In this area inhabited by millions, built in one of the most dangerous volcanic regions on earth, all life is over.

The Campi Flegrei caldera is a supervolcano. Although there’s no picture-postcard volcanic cone, hidden beneath the seemingly placid landscape lies a volcano of immense power. While a new eruption here would be more likely to result in the creation of another Vesuvius-like cone, the worst-case scenario could see it obliterating much of life in Europe.

In this eventuality the Earth’s surface would swell and crack and a series of small eruptions would cause the four-mile-wide caldera floor to collapse into the larger magma reservoir, which would in turn push more magma to the surface.

The last time the ground gave way like this, 39,000 years ago when the caldera was formed, it created the cliffs that the postcard town of Sorrento stands on now – volcanic deposits over 300ft deep. If the same kind of eruption happened today, this part of Italy could cease to exist, and the ash clouds would blot out the Sun and lower the Earth’s temperature. Life in the UK as we know it would end. We would lose our livestock, crops and three-quarters of our plant species, plunging us into a new dark age of rioting, starvation and perpetual winter.

Now an international team, including scientists from the UK, wants to drill down inside the caldera to try to better understand exactly why part of it has risen 10ft since 1969. The area at the epicentre of the swelling has seen whole streets of houses crumble and collapse. The threat is imminent. The last time the ground rose like this (between 1430 and 1538) there was an eruption that caused the formation of a new volcano.

Geophysicist Renato Somma at an abandoned building destroyed by sulphurous deposits from the caldera

Key to the operation is British volcanologist Chris Kilburn, from University College London, who lived in Naples for 20 years. He’s part of a long tradition of UK volcanology, which stretches back to the grand tour of the 18th century, when Sir William Hamilton provided some of the first scientific observations of Vesuvius. The UCL group are now world leaders in rock physics – especially in understanding how the Earth’s crust deforms and breaks – which makes Kilburn a vital member of the drilling team.

‘Right now we may well be in another period of uplift,’ he says. ‘If it occurs as before, we might expect another 60 years’ worth of unrest, and possible earthquakes and eruptions, with two or three more episodes and uplift to occur in the next ten years. We have to presume we have a few more decades of unrest, and if this is going to be the case, then we have to get more data about the volcano now.’

Kilburn and the other scientists’ work may well be crucial if the people of Naples – and the rest of Europe – are to avoid another Pompeii scenario. Yet despite the urgency, the mayor of Naples has just dramatically halted the project. Drilling was to begin this month on the site of the old Bagnoli steel mill, on the eastern part of the caldera, but was stopped following the very public objections of a sole local scientist, who has warned that the drilling itself could actually trigger an explosion that could destroy the city.

The people of Naples seem to be damned if they do and damned if they don’t, but is it really possible that one simple drill hole could cause an eruption that could end life as we know it in Europe?

Pisciarelli, near Pozzuoli – the centre of the caldera

Renato Somma, of the National Institute of Geophysics and Volcanology in Naples, pushes the Fiat through the gears as we wind our way through the grounds of a hotel and health club built on the side of the Solfatara crater. Once fashionable, the hotel was used by U.S. Naval officers until a rise in the ground of 6ft led to an earthquake that damaged the base, and saw the U.S. Navy relocate 20 miles away from Naples.

The road runs out, and Somma stops the car beside an abandoned earthquake-damaged building. To our right the hill continues upwards. To our left is a five-a-side football pitch and the valley below. The only curious thing is the colossal plume of steam energetically billowing upwards from behind the pitch. We walk alongside the ground and duck under a loose section of wire fence, watching the steam as it swirls in the wind.

The area where scientists want to drill towards the magma

Suddenly the Tarmac ends and yellow and white volcanic stone cracks underfoot like stale bread. A few steps further and we hit a wall of sulphur, which rolls over us in invisible waves, collecting in our throats and turning our stomachs.

Where once there was green hillside there’s now an atrophic scar of sponge-like volcanic rock. At the lowest point of the scar gurgles an inhospitable pool of boiling muddy water, where bubbles of gas rise to the surface and pop like blisters. Somewhere below, magma and water are meeting and making CO2, which filters through the sponge and prevents any kind of plant or animal life from living here.

I tell Somma I’m disappointed there’s no lava: you see a volcano, you want lava – it’s like a Martini without the olive. He laughs.

‘This is even more dangerous than the lava flow,’ he says. ‘Below here we have a risk of hydromagmatic eruption – when the magma and water meet you have a more explosive pressure than with magma alone.