The Catastrophe

On the morning of the 24th of August AD 79 the long- dormant volcano of Mount Vesuvius blew up. Just after midday on August 24, fragments of ash, pumice, and other volcanic debris began pouring down on Pompeii, quickly covering the city to a depth of more than 9 feet (3 meters) and causing the roofs of many houses to fall in.

Surges of pyroclastic material and heated gas, known as nuées ardentes, reached the city walls on the morning of August 25 and soon asphyxiated those residents who had not been killed by falling debris. Additional pyroclastic flows and rains of ash followed, adding at least another 9 feet of debris and preserving in a pall of ash the bodies of the inhabitants who perished while taking shelter in their houses or trying to escape toward the coast or by the roads leading to Stabiae or Nuceria.

Thus Pompeii remained buried under a layer of pumice stones and ash 19 to 23 feet (6 to 7 meters) deep. The city's sudden burial served to protect it for the next 17 centuries from vandalism, looting, and the destructive effects of climate and weather (Pompeii AD 79).