On the morning of August 24, A.D. 79, a great noise was heard in the area around Vesuvius. A mushroom shaped cloud of gas and volcanic rock rose high in the air, darkening the sky. A shower of burning cinders and rock fragments covered Pompei. It lasted until the next day, caving in roofs and claiming its first victims. The Pompeians tried to take shelter in the houses or hoped to escape by walking on top of the layers of pumice stones constantly being formed, which by this point were more than 2 meters deep. But at dawn on August 25, a violent explosion of toxic gases and burning cinders devastated the city. It infiltrated everything, taking those who were trying to flee by surprise and making every form of defense vain. A shower of very fine ash was deposited everywhere to a depth of more than six meters, enveloping everything and adhering to the forms of the bodies and even the folds of their clothes. When, two days later, the fury of the elements abated, the entire area had a different aspect: a white blanket covered everything; the Sarno river was trying to find its course again after having been filled with volcanic rubble; and the coast, submerged by the material spewed forth by Vesuvius, had encroached on the sea! The whole city was declared off limits, to protect the property of the survivors, but clandestine diggers tried to plunder it anyway. For a long time the human presence was rare and marginal, and only under the emperor Hadrian, around 120 A.D., was at least the road system in the area reopened to traffic. We have an eye-witness report of the catastrophe in a letter from Pliny the Younger to the Roman historian Tacitus, in which he tells about the death of his uncle, Pliny the Elder, as he was trying to bring aid to the devastated cities. If you would like to hear it, press 103 and then play.
fonte: pompeiisites.org