Vesuvius is remembered for the eruption of 79 AD, a devastating eruption that led to the disappearance of Herculaneum and Pompeii.
Two letters by Pliny the Younger, who was at Misenum during the eruption of Vesuvius in 79 AD, are the only written evidence of what really happened during those terrible days.
Vesuvius eruption 79 AD: what happened
Uncle Pliny the Elder, commander of the Roman fleet at Pozzuoli, came to the aid of the Pompeians and Herculaneum, and he too fell victim to the force of the eruption.
The letters tell us that the days before the eruption there had been earthquake tremors that no one had noticed because they were quite frequent in the area. The night before the tragedy, however, there was a very strong tremor that caused a lot of damage to buildings. The beach had receded and many marine animals were lying on the dry sands. At first light a black cloud with fire was visible. Later the cloud lowered and hid Capri and the promontory of Miseno. Ash was already falling and it suddenly became night. A faint glow appeared, but it was not daylight but firelight.
The contents of the letters, which are very detailed, have helped volcanologists to reconstruct what happened during the tremendous eruption of Vesuvius in 79 A.D.
On 24 August 79 AD, Vesuvius began to erupt violently. A column of rocks, smoke and gas rose into the sky. The column exceeded 3 km in height and when it collapsed to the ground it caused a dense and heavy rain of debris to fall on the surrounding area. Two Roman cities, Pompeii and Herculaneum, were destroyed and buried.
When the eruption of AD 79 occurred, people did not know that Vesuvius was a volcano. In fact, the Romans didn’t even know what a volcano was and didn’t even have a vocabulary word for it.
Before the eruption of 79 AD, the Romans believed that Vesuvius was simply a mountain with very fertile soil. The small earthquakes that were frequently felt were not considered a manifestation of the volcano’s activity, but were interpreted as divine signs, sent by the gods, to bring them back on the right path. Nobody knew that the earthquake was part of a long process linked to the eruption of Vesuvius.
The first moments of the eruption of Vesuvius in 79 AD brought chaos. People tried to save themselves but it was all in vain. Some tried to save themselves by moving as far away from the area as possible. The ash was everywhere, however, and most people took refuge in their homes, hoping that they would be safe. The eruption was very rapid and as the minutes passed the ash and rocks accumulated everywhere. The roofs of the houses, and then the structures, began to collapse. Outside, those who tried to get away and save themselves met an even more terrible end.
The next day, 25 August 79 AD, the column of ash that had been rising from the crater for 12 hours became too heavy to remain in the air and collapsed to the ground. Within 12 hours of the start of Vesuvius’ eruption, an avalanche of incandescent gas, rock and ash formed, known as a pyroclastic flow. This incandescent wave, travelling at hundreds of kilometres per hour, destroyed everything in its path. In Pompeii, many victims probably suffocated for a few minutes before being killed by the flow. In Herculaneum, however, the inhabitants suffered a worse fate. Although Herculaneum was located 12 km from Vesuvius, the pyroclastic flows destroyed the city in a very violent way. The incandescent wave swept over Herculaneum at even higher temperatures than Pompeii. The monstrous pyroclastic flow killed every living thing, including bacteria and viruses. People died instantly. All bodily fluids instantly vaporised and escaped to the outside world. Blood boiled in the brain with such force that the skull exploded. The steam then cooled the ashes and the surrounding area and fell back onto the bones, locking them in the position they had assumed before dying.
Herculaneum is better preserved than Pompeii precisely because of the difference in temperature of the pyroclastic flow that hit the two cities.
One of the paradoxes of the incandescent wave of the eruption of Vesuvius in 79 AD is that the places where it reached higher temperatures were better preserved. Herculaneum, for this reason, is to be considered a city hibernated in time.
