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Scientists solve mystery of volcano's "natural deaths"

Xavier Bosch, Barcelona

Scientists believe they have pieced together the chain of events that can explain some of some of the most bizarre and mysterious deaths in recorded history. When Mount Vesuvius erupted in ad79, thousands of people evacuated areas around the volcano, but about 2000 were killed. Many inhabitants of Pompeii died of suffocation.

However, the skeletons of some victims from nearby Herculaneum who had taken refuge in nearby caves have puzzled scientists since they were discovered 20 years ago. They were found in natural, relaxed postures, with no signs of mechanical impact nor of the involuntary self protective responses or contortions of agony that one would expect. No one understood why. The conclusions of an interdisciplinary team of scientists, published in Nature (2001;410: 769-70), is that the shock of the heatwave stopped the activity of their vital organs before their involuntary responses could be activated.

At the time of the Vesuvius eruption, a cloud of a swiftly moving mixture of volcanic gases and ash with a temperature of 500 C swept over the town of Herculaneum and its beach. The 80 intact skeletons on which the study was performed were unearthed from the volcanic ash in which they were buried in caves used as boat chambers along the beach. The research was also partly based on observations of fire victims, ancient burnt bones and human bone tissue, cremations, and victims of pyroclastic flows (flows of hot ash, blocks, and gases down the slopes of a volcano) as well as on teeth that were heat treated in the laboratory.

Alberto Incoronato of the University of Naples Federico II, who led the research, said that skeletons "exhibited contractions of the hands and feet and long bone fractures due to exposure to a high temperature, and skull fractures due to violent brain vaporisation." In fact, the heat of the ash was just sufficient to vaporise most of the organic matter.

"They died instantaneouslyin less than a fraction of a seconddue to fulminant shock caused by the entrapment within the 500 C ash cloudnot due to suffocation as so far believed. They had no time to display any defensive reaction," he added.

(Credit: CORPORATION OF LONDON/HERITAGE-IMAGES) A lurid Victorian image of Vesuvius erupting