New excavations show far more extensive damage than that found at the more famous site of Pompeii, buried in A.D. 79.

It could happen again, affecting metropolitan Naples, where 3 million people live, and officials are not planning properly for it, the researchers write in this week's issue of the Proceedings of the National Academy of Sciences.

"Evidence shows that a sudden, en masse evacuation of thousands of people occurred at the beginning of the eruption," Giuseppe Mastrolorenzo and colleagues at the Istituto Nazionale di Geofisica e Volcanologia-Osservatorio Vesuviano wrote.

"Everything was there," added Michael Sheridan, a geologist and hazard assessment expert at the University at Buffalo in New York who worked on the study.

"They even left animals in cages," Sheridan said in a telephone interview.

"Scenes of everyday life, frozen by the volcanic deposits, testify that people suddenly left the village: the molds of four huts, with pottery and other objects left inside; skeletons of a dog and nine pregnant goat victims found in a cage; and footprints of adults, children and cows filled by the first fallout pumice," the researchers wrote.

"I think what they probably had was a couple of days (to get out). There are lots of skeletons but thousands and thousands of footprints," Sheridan said.

The footprints would have been left as survivors ran through the mud deposited in the explosion. Ash filled them, preserving them for archeologists to find.

VIGNETTES OF LIFE

The site at Pompeii is famous for the vignettes of everyday life preserved in the ash - writhing victims, everyday households and even a brothel with lurid murals.

Several sites dug up in farmland and pumice quarries in the surrounding area show similar preservation of the much-older Bronze Age civilization, Sheridan said. "This is really a slice into the life of the people who lived there," he said.

Vesuvius would have shaken as the strength of the eruption built. A column of ash would have spewed high up into the atmosphere and then rained down for many miles around.

Clouds of steam and ash would have formed on the flanks of the volcano and rolled down, leaving steaming deposits as far away as 9 miles (15 kilometres).

These would have cooled toward the edges, allowing escape, but closer in, nothing would have survived, Sheridan said. "The people in there would have cooked," he said.

Looking at Vesuvius now, it sits directly across the Bay of Naples from the city and its extensive suburbs.

"If you look at the structure of the volcano, it now forms an amphitheater that is facing west (toward Naples). This has a very strong effect on blast and flows," Sheridan said.

"It is almost as if they would be focused toward Naples."

Sheridan said the disaster that followed Hurricanes Katrina and Rita on the US Gulf Coast shows officials do not plan adequately for natural disasters.

"It is obvious they were not paying attention to what happened or have plans for something a little larger than what they expected," he said.