In the towns and villages that dot the side of Mount Vesuvius, the volcano that buried the ancient Roman cities of Pompeii and Herculaneum, life seems normal enough, except there's expectation in the air. Ugo Corati, who has lived and worked on the mountain all his life, was 12 years old when it erupted, in 1944. It was a bad time. A slow stream of lava destroyed 800 homes and the villages of San Sebastiano and Massa di Somma, and killed a few dozen people. Since then, scientists have installed all sorts of fancy equipment to monitor the mountain for signs of trouble, and local authorities regularly sound sirens and lead evacuation drills. Corati, sipping espresso in a local cafe, doesn't seem at all reassured by this activity, but neither is he particularly troubled by the danger. "What can you do about it?" he says with a shrug. "All these safety measures and all this monitoring equipment are in place, but if the mountain goes, we're all as good as dead."
A chilling assessment, and it gets chillier. Earlier this month volcanologists said the mountain was beginning a new cycle of volcanic activity that could trigger an eruption "at any time." And this one will be nothing like the slow dribble of lava in 1944, they predict; it will be the biggest explosion in 2,000 years. The news is not good for the 2 million people who live and work within sight of the crater. The area around Mount Vesuvius is the world's most densely populated volcanic region. A big eruption could kill a million people in minutes, says Edoardo Del Pezzo, research professor with the Vesuvius Observatory in Naples. "We expect that a wide area could be destroyed in a few minutes."
This scenario sounds frighteningly similar to A.D. 79. Twenty thousand residents of Pompeii and Herculaneum thrived on the mountain's unusually rich soil, which they probably attributed to the blessings of Fauna, the goddess of farming and fertility. In August of that year the gods got ugly. Wells dried up, mountain streams stood still, birds and dogs went silent, the ground rumbled. One day hot gases, ash and pumice shot 30 kilometers into the sky. Ash rained down on Pompeii at the rate of six inches per hour, and then came the lava. In 1961, archeologists unearthed impressions of ancient Romans buried alive while trying to flee the mountain, their mouths agape and arms extended in poses of desperation.
Mount Vesuvius continued to erupt every hundred years or so until 1037, when a 600-year lull ensued, followed by a sudden eruption in 1631 that killed 4,000 people. It also kicked off a new cycle of eruptions, 21 in all, that ended in 1944. Despite constant monitoring since then, scientists didn't detect trouble until Gabriele Paparo, a geologist with the National Research Council, finished a three-year study this summer. Vesuvius' last eruption was relatively gentle because it was driven mainly by hot molten rock, or magma, percolating up from beneath the earth's crust and causing slow-moving lava flows. Paparo found a more disturbing development: gases building up beneath the mountain are setting the stage for a much more violent eruption. As the ground gets hotter from volcanic activity, it swells, compressing the gases that fill up the cracks. The tidal pull from the sun and moon raises and lowers the water table, increasing the pressure further. Eventually, the mountain's lava plug will blow. Del Pezzo expects the eruption to be about one fifth as powerful as the one that devastated Pompeii--though big enough to destroy a seven-kilometer ring around the crater within 15 minutes.
Will residents get caught by surprise? Not if the scientists can help it. They are using radar satellites to monitor subtle swellings of the ground. They've slipped fluid-filled cylinders into cracks and holes to measure stresses and strains. They've put out seismic antennas to pick up the slight-est tremors and a new artificial nose to sniff gases emanating from fissures in the ground. They're looking for "anomalies"--any sudden change that might signal an eruption in progress. Del Pezzo expects to see such "precursor phenomena" a month or so before a big eruption. Once Observatory scientists notify the civil authorities, "a government commission evaluates the situation, and gives the alert," he says.
The Naples emergency management center has an evacuation plan, and officials have been testing it for months. At the sound of the sirens, residents say they feel a flutter of panic and hesitantly look up toward the summit in search of smoke. Reassured, they then hop into their rusty old Fiats and start on the 10-kilometer trek down the mountain. Along the narrow winding roads they meet many obstacles--farm animals, old tractors puttering along, a motorist with a flat tire. At an evacuation drill a few weeks ago, residents were held up for half an hour by a sheep herder and his flock. The drills have the air of farce. Perhaps it's gallows humor. If the mountain blows, the roar will be deafening, the smoke billowing, the shower of ashes hot. It's hard to imagine how residents will avoid panicking, and harder still to imagine them getting down in the allotted 15 minutes.
In the meantime, residents enjoy the mountain's rich tephra soil, a byproduct of volcanic ash and a few thousand years of weathering. Between rows of grape vines, farmers plant tomatoes, fava beans, cauliflowers and onions; orange and lemon trees, herbs and flowers grow on the borders. The harvests are so profitable, say residents, they're worth the risks--though they're still anxious to know when the mountain will blow. Del Pezzo, who lives in Naples, within the zone of destruction, says the signs don't point to an imminent eruption. But, he admits, "it is not possible to actually answer the question of when it will erupt." He only knows it will.