Findings from the archaeological and stratigraphic surveys on materials deposited during the eruption od Vesuvius in 79 AD compared with Pliny the Younger’s description of the event to Tacitus have shed light on the progression of consequences for people and things during the development of the eruptive event.
On the mooring of 24 August 79 AD, a sudden tremor abruptly interrupted the daily routine of the inhabitants of Pompeii, This was followed shortly afterwards by a tremendous blast signaling the beginning of a violent eruption with a column of lapilli rising over 20,000 meters onto the sky. Carried by the wind, this cloud of lapilli hailed down upon Pompeii, submerging the city in just a few hours in some three meters of material. The roofs of many houses caved in under the weight, often crushing and killing those who had taken refuge within. But the worst was yet to come. At dawn of the following day, the first pyroclastic flow, composed of hot gas and fine ash, hit Pompeii and sealed the fate of every person and animal it encountered. The burning ash clogged the lungs and caused death by suffocation. Shortly thereafter, when already no living thing was left in the city, a second flow, much more powerful than first, fell with fury upon the walls of the town toppling or sweeping away their upper portions. It has been calculated that this pyroclastic flow was probably travelling at speed of between 65 and 80 kilometers per hour as it engulfed and carried off objects, roofing tiles and even the bodies of the dead Pompeians. Other surges hit Pompeii in waves after the city had already been destroyed. In the end, Pompeii was left buried under 5-6 meters of ash and lapilli in a desolate grey landscape whose only features were a few protruding walls.