The Eruption of Vesuvius

1. The Eruption of Vesuvius www.misterconnor.org

2. catastrophe The eruption of Vesuvius started on the morning of 24 August 79 CE. Witnesses heard a loud bang and cracks emerged in the sides of the mountain. The top of Vesuvius then exploded, sending volcanic boulders into he air. Pliny the Younger notes a black cloud, like “an umbrella pine” formed in the sky. Ash and pumice began to fall like rain. It piled up, but was not lethal. It did trap people in their homes. Then lava emerged from the sides of the mountain. Ash and pumice continued to rain down. Finally, the cloud began to collapse and all the superheated material within it rushed down the sides of the mountain in pyroclastic surges which engulfing Pompeii.

4. Ignorance • The Pompeiians had not seen it coming, so were unready for it. • There were plenty of signs leading up to the eruption that we could use now, but of which the Romans were ignorant.

5. Witnesses • The eye-witness accounts of Pliny the Younger allow us to understand the eruption. • He also provided accounts of the reaction to the eruption, and the real-life drama of citizens facing the catastrophe.

6. The Reaction of the Plinys • Pliny the Elder was so unprepared for it that he was having lunch after a bath when he first noticed the eruption, at Misenum, some fifty kilometres away. • His first impulse was not of emergency, but of curiosity. • He and those on his boat had not anticipated the scale of the disaster. • In Pliny the Younger’s account, he mentions early signs of the volcano becoming active. He mentions earth tremors, 'which were not particularly alarming because they are frequent in Campania‘. • Here, we get an impression of the scale of Roman ignorance to the connection between seismic and volcanic activity.

7. Nowadays • Today, Vesuvius is under permanent observation by volcanologists who monitor the changes in seismic and volcanic activity. • Any increase in magma (molten rock) below the surface of the Earth causes earth tremors, earthquakes and volcanic eruptions. • Now, it is possible to forecast volcanic eruptions well ahead of the event itself.

8. Signs? • The longer the time between eruptions/ earthquakes means the eventual explosion will be greater. • Frequent, low-level tremors are a healthy sign that this pressure in the magma chamber in the earth is being released. • The reason for the scale of the 79 CE eruption was the extended period of volcanic inactivity before. • A long interval combined with mounting seismic activity is a sure sign of impending disaster.

9. Signs? • A long period of volcanic inactivity was cause for the Pompeians to believe everything was fine. • They did, however, note that the mountain was smoking ahead of the eruption.

10. Signs? • Recent excavations at the site of the new NATO base at Gricignano, on the north of the Bay, have revealed two catastrophic eruptions that preceded that of 79, and wiped out the populations of a densely occupied territory. • The most important earlier eruption, known as that of the 'Avellino pumice' occurred around 1800 BC; several sites, especially one near Nola, reveal the destruction of Bronze Age settlements, with their huts and pots and pans and livestock.

11. Signs? • As we have seen, the Romans were extremely interested in augury, omens, portents, sooth-sayers and other forms of predicting the future. • Cassius Dio (155 CE – 235 CE) wrote of giants roaming the land in the period leading up to the eruption. • In Roman mythology, rebellious giants, defeated by the gods, had been buried in the land of southern Italy, and this explained its volatile nature.

12. Signs? • A few years before the eruption, Seneca wrote a book on the causes of earthquakes. • He was writing at the time of the 63 CE earthquakes of Campania which had been very damaging to towns in the Bay of Naples, including Pompeii and Herculaneum. • Seneca said that earthquakes in different parts of the world could be connected, and were possibly linked to storms, but saw no link to volcanic eruptions.

13. Response • We know of the damage done by the 63 CE eruption because of the many repairs to buildings which date from that year. • Some buildings were reduced to rubble entirely, then given over to farm land. • Others escaped with less dramatic damage, though upper floors were badly affected.

14. Ongoing Repairs • Damaged houses were being extensively repaired and redecorated at the time of the AD 79 eruption, and there was a comprehensive programme of restructuring of public buildings in the Forum of Pompeii.

15. Ongoing Repairs • From AD 63 onwards there were continuous repairs. • We now know that in the period running up to the volcanic eruption there was some seismic activity which damaged building which had already been repaired. • In the house of the Chaste Lovers, archaeologists discovered that the oven of a bakery had suffered major cracking; it had been repaired, but had then been damaged again - and building work was already in progress to mend this new damage. • In the same block, three cesspits in the street (which linked to latrines in the houses) had been dug out immediately before the eruption, presumably to restore them to full functionality.

16. Ongoing Repairs • In the main street, an open trench was found, cutting the entire length of the walkway as far as a water-tower at the crossroads: • seismic activity had interrupted the water supply, but people had been hard at work repairing it. • A frequent sight in the excavated houses of Pompeii is that of heaps of plaster, which must have been brought in ready for new decoration.

17. Don’t Worry… • At the time of the eruption, Pompeians were going about the business of repairing their city – they were not so worried that they saw the eruption as a sign that they should get out. • They do not seem to have been worried. • The economy of the Bay was booming, and the port of Puteoli was one of the biggest hubs of Mediterranean trade.

18. The Eruption • Pliny depicts his uncle as a model of Stoic resolve: calmly sailing directly into the danger zone (where he subsequently died), and taking a bath, dinner and sleep while the catastrophe unfolded. • But all around him is panic - Rectina in her villa, Pomponianus in his.

19. The Eruption • Pliny the Younger also stayed calm. • At his mother’s begging they finally left the villa to move north, by which time a dense cloud of ash has blackened the sky. • Around them they hear people screaming in fear and pain.

20. The Eruption • The eruption lasted for more than 24 hours from its start on the morning of 24 August. • The citizens who left immediately, and travelled light, had a chance of survival. • The initial rain of ash and pumice was not lethal. • It seems likely that most of the citizens who remained believed there would be nothing more dangerous than this.

21. The Eruption • At around midnight, the first pyroclastic surge occurred. • These are waves of hot ash, pumice, rock and volcanic gas which rushes across the ground at speeds up to 100km/h. • They meant certain death for the remaining citizens.

22. The Eruption • Subsequent pyroclastic surges reached Pompeii, asphyxiating those who had survived the fall of 3m (10ft) of pumice, and were fleeing across the open in the dark, or hiding beneath roofs. • The waves that followed smashed flat the upper floors of houses, and left the corpses encased in successive blankets of gas and pumice.

23. Death Toll? • It is estimated that 2,000 people died in the disaster. • We don’t know for sure exactly how many people were killed. • The Romans were used to receiving news of thousands of dead in battles. • Even by these standards, the eruption was considered exceptional. • The corpses found by archaeologists in Pompeii or Herculaneum are only a small sample: the destruction encompassed the entire landscape south of Vesuvius to the Sorrentine peninsular. • As many died in the countryside or at sea as in the cities. Even as far north as Misenum, the ash lay deep in drifts.

24. After the Eruption • The effect of the eruption was evidently totally traumatic, as is shown by the failure to reoccupy the sites of the cities destroyed. • It was normal practice to rebuild the cities of this region after even the most massive earthquakes; but neither Herculaneum nor Pompeii was reoccupied.

25. Looting the City • Instead, the site of Pompeii was riddled with tunnels by explorers, not by modern explorers as is often imagined, but by the Romans themselves after the eruption. • Room after room of the city's buildings had holes hacked through the walls by tunnellers, and though Pompeii has richer finds than any other Roman site, it is a city already extensively sacked by looters.

26. Resumption of Life • Other cities in the area resumed commercial life, and prospered. • However, it was never again as popular as in the two centuries before the disaster, the time when it had been the playground of many rich senators and emperors.

27. The Skinny • Warning signs: Avellino pumice of 1800 BCE, earthquake of 63 CE, earth-tremors, disrupted water suppy, smoke rising from the summit of Vesuvius. • Pompeians did not panic – they did not associate the signs with volcanic eruption. • The cloud blocked out the sun. • The initial fall of ash and pumice was not enough to frighten citizens to leave, though trapped many. • Consequently, the city was largely populated when the pyroclastic surges began. • Most looting of the town was done in the immediate aftermath.

28. Sources • https://en.wikipedia.org/wiki/Eruption_of_Mount_Vesuvius_in_79 • http://www.bbc.co.uk/history/ancient/romans/pompeii_portents_01.shtml • https://en.wikipedia.org/wiki/Plinian_eruption