Survey: Eruption of 79 CE and its Impact

Question 1

The Date

Answer 1

It was widely believed that the date of the eruption of Mt Vesuvius was 24 August, 79 AD.

However, a charcoal inscription was found in October 2018 with the inscription “16th day before the calends of November, suggesting that the eruption was after 24 August. Massimo Osanna explained that the inscription must mean that it was made in 79 AD as rain or passerbys would have removed it.

Other issues of contestability include:

• Pliny’s letters being dated to 3 or 24 November, or 24 August
• Dio Cassius mentioned an autumn eruption 150 years after the event
• Food remains and winter clothing indicate an autumn eruption
• A silver denarius of Titus was found in a coin hoard, acclaiming his as imperator, an announcement that would not happen earlier than September

Question 2

The Plinian Phase in Pompeii

Answer 2

1. Mt Vesuvius erupts
2. A column of ash and pumice forms, 20-30km in the air (umbrella pine)
3. For 18 hours, pumice and ash is blown by winds over Pompeii and Stabiae, depositing at a predicted rate of 15 cm/hour.

Question 3

Impact of the Plinian Phase on the town of Pompeii

Answer 3

Pompeii was covered to an average depth of 2.5 metres of pumice and ash. However, it was not completely destroyed until the next phase.

Question 4

Impact of the Plinian Phase on the people of Pompeii

Answer 4

Despite ash and pumice blackening the sun and sky, 18 hours was sufficient time for many to escape.

Many chose to remain and take shelter, causing them to become trapped.

• Roofs and buildings began to collapse from the weight of pumice stones, killing many.
• Some died from being hit by falling stones (laepelli).
• A total of 394 bodies have been found in the initial pumice layer from the Plinian Phase, bt it is unknown how many escaped people survived.

Question 5

The Plinian Phase in Herculaneum

Answer 5

Herculaneum was spared the thick pumice layer that killed hundreds in Pompeii because the wind blew in the opposite direction.

They would have instead experienced:

• Earthquakes/tremours
• Ash cloud towering over and beginning to block the sky
• Lightning

Question 6

Impact of the Plinian Phase on the town of Herculaneum

Answer 6

Minor impact

Question 7

Impact of the Plinian Phase on the people of Herculaneum

Answer 7

Being closer to the volcano meant that people had to travel further in order to reach safety.

Some, like in Pompeii, chose to take shelter and remain.

• Many sheltered in boat sheds, sealing their fates

Question 8

The Pelean Phase in Pompeii

Answer 8

This phase was the most destructive due to the collapse of the volcanic column and violent pyroclastic surges, which included the following:

• Surge 1-2: Did not reach Pompeii but reached estimate speeds of 100km/h
• Surge 3: Stopped just before the Herculaneum Gate in th north-west
• Surge 4: Overwhelmed the city and killed everyone who remained, either through the extremely high temperatures or toxic gases (carbon dioide + hydrogen chloride)
• Surge 5-6: Delivered 1.8m of volcanic material while also knocking the tops off buildings

Question 9

Impact of the Pelean Phase on the town of Pompeii

Answer 9

• Covered in 5m of volcanic debris (clearly stratified layers from each surge)
• Wiped off the face of the earth for the next 1500 years

Question 10

Impact of the Pelean Phase on the people of Pompeii

Answer 10

Causes of death ranged but included:

• crushed by falling roofs
• crushed by collapsing columns (priests of Isis)
• asphyxiation
• thermal shock

Question 11

The Pelean Phase in Herculaneum

Answer 11

While this phase was similarly mre destructive than the Plinian Phase in Herculaneum, the only notable surge is the first:

• Surge 1: Sped down Mt Vesuvius at speeds of 100km/h, covering Herculaneum in 3 metres of hot ash (eventually 25 metres), vaporising everyone
• Surge 2: Another 1.5 metres of ash is deposited

Question 12

Impact of the Pelean Phase on the town of Herculaneum

Answer 12

• The force of the surge topple some buildings, rmeoved some roof tiles and moved stone blocks.

Question 13

Impact of the Pelean Phase on the people of Herculaneum

Answer 13

• Five minutes after the collapse of the volcanic column, the first surge hit the town with temperatures of 400-500°C, causing instantaneous death through thermal shock.
• In 1982, 300 skeletons were found on the beach in vaulted chambers, who turned to charcoal from the heat surge.
• Death by asphyiation occurred in two minutes as their windpipes become blocked by mucus and ash.
• Death by thermal or fulminant shock caused the blackening of the inside of victim’s skulls and cracking of teeth,

Question 14

Deaths

Impact of the Eruption

Answer 14

Total casualties is unknown.

Pompeii
1. Pompeii’s usual population is 20 000, not including possible summer visitors.
2. 90% of people escaped, meaning approx. 2000 people died of various causes. Modern reevaluations reduced this number to 500 within Pompeii itself.

Herculaneum
1. It was first believed that almost all inhabitants escaped.
2. Excavations near the shoreline revealed hundreds of skeletons (so maybe no one survived…)

Question 15

Burial of Towns

Impact of the Eruption

Answer 15

The eruption destroyed many towns of Campania, including Pompeii, Herculaneum, Oplontis, Sora, Tora, Taurania, Cossa, and Leucopetra.

This changed the entire geography of Campania by raising the sea beach and turning the Sarno River back from its course.

Pompeii was once a seaside town but now lies far inland. Herculaneum took much longer to discover as it was under the modern city of Erculano.