Vesuvius 79 AD

Mount Vesuvius is best known for its 79 AD eruption which buried Pompei, Herculaneum, Oplontis and Terzigno. There is only one account of the eruption, written in two letters, by Pliny the Younger to the historian Tacitus. Pliny the Younger observed from Misenum; across the bay from Herculaneum.

The eruption started about midday on the 24th of August 79AD and continued for 19 hours. Initially a column of ash filled the sky. Because of the wind direction Pompeii felt the effects of the eruption before Herculaneum. Most people were buried in houses as lapilli and ash was rained from the sky. When the column reached a height of over eighteen miles (28.9 km) it collapsed sending a pyroclastic surge down the mountain side. In Herculaneum the surge burned away people’s skin and muscle leaving only their skeletons. Finally pyroclastic flows erupted down the mountain. Pyroclastic flows are faster than surges and consist of hot ash, rock fragments, and gas. They can reach speed of up to 100 miles/hour (161km/h) and temperatures of up to 1000 degrees F (537 degrees C). Everything in a pyroclastic flows path is knocked down or burnt away. It was the flows that helped to preserve bones and organic matter, like wood and the fibre of clothing, by creating a ‘seal’ of volcanic debris on top of the ruins.

Excavations at Pompeii, the other towns and surrounding area revealed a large number of holes in the volcanic deposits. These represented bodies of people and animals that were buried by the hot ash. The ash compacted and became solid before the bodies decayed leaving behind a mold of the deceased. Many of the molds were filled with plaster to create a casts of the victims of the eruption.