Ancient Rome · 79 CE (traditionally 24 August)
What Happened at Pompeii When Vesuvius Erupted?
In short
- Vesuvius erupted in 79 CE, burying Pompeii under pumice and Herculaneum under surges of hot ash.
- Pliny the Younger described the eruption in letters to Tacitus, written about 25 years later; his uncle died trying to rescue others.
- The traditional date, 24 August, may be wrong: an inscription found in 2018 may point to October, though the debate continues.
About a quarter of a century after he watched Vesuvius erupt, a Roman lawyer sat down to describe it for the historian Tacitus. Pliny the Younger had been seventeen, and his uncle had sailed straight toward the mountain and never came back.
A mountain no one feared
Pompeii was a prosperous town near the Bay of Naples, with perhaps ten to twelve thousand people, though estimates vary. Its walls were scrawled with election slogans, its streets had bakeries, bars and brothels, and its amphitheatre could seat about twenty thousand. In 62 or 63 a severe earthquake had damaged many buildings, and repairs were still going on.
Few people there can have feared the mountain. The geographer Strabo, writing a few decades earlier, noted that its summit looked ash-coloured and eaten by fire, as if it had once burned. But Vesuvius had not erupted in anyone's memory or records, and farms covered its lower slopes.
The cloud
Pliny the Younger was staying at Misenum across the bay, where his uncle Pliny the Elder commanded the Roman fleet. Early in the afternoon a cloud rose above the mountain. In Pliny's words, it was shaped like a pine tree: a tall trunk spreading into branches at the top.
The elder Pliny, a scholar and naturalist, ordered a fast ship to take a closer look. Then a message came from a woman named Rectina, whose villa lay at the foot of the mountain, begging for rescue. He launched warships and steered toward the danger through falling ash and pumice. Unable to land, he went on to Stabiae, where he died the next day; his nephew believed thick fumes had choked him.
Pumice, then the surges
Volcanologists have reconstructed the eruption from the layers it left. From early afternoon until the next morning, pumice and ash rained on Pompeii, piling up to about two and a half metres. Roofs gave way. Many people fled, but some stayed, sheltering indoors or hoping it would pass.
Then came the deadliest phase: avalanches of superheated gas and ash, called pyroclastic flows and surges, that raced down the mountain and swept through the town in minutes. Those that struck Herculaneum during the night buried it under some twenty metres of volcanic material. Excavators have found the remains of more than a thousand people at Pompeii alone.
Which day?
The usual text of Pliny's letter dates the eruption to the ninth day before the Kalends of September, 24 August, though the manuscripts disagree. In 2018 archaeologists at Pompeii found a charcoal scrawl that seems to be dated 17 October, and finds such as autumn fruits point the same way. Many specialists came to favour an autumn date, but a 2024 study argued that the August date still stands, and the question is not settled.
Pliny's account needs the same care. He wrote around 106 CE at Tacitus's request, so the story reaches us as a man's memory of what he saw and heard at seventeen, not as a diary.
Rediscovery
Titus sent senators to organise relief for Campania, but the buried towns were never rebuilt and were slowly forgotten. Excavation began at Herculaneum in 1738 and at Pompeii in 1748, at first as treasure-hunting for the Bourbon king of Naples.
In 1863 the archaeologist Giuseppe Fiorelli realised that the ash had hardened around bodies that later rotted away, leaving hollows. Pouring plaster into them produced the casts that visitors see today. Pompeii shows the ordinary life of a Roman town in a way no author could.
In their own words
“A cloud, from which mountain was uncertain, at this distance (but it was found afterwards to come from Mount Vesuvius), was ascending, the appearance of which I cannot give you a more exact description of than by likening it to that of a pine tree.”
Pliny the Younger, Letters 6.16, to Tacitus, c. 106 CE
Translation by William Melmoth (first published 1746), revised by F. C. T. Bosanquet; in the Project Gutenberg edition this is letter LXV. Pliny describes what he saw from Misenum at seventeen and what he learned of his uncle's last hours, writing a quarter century later at Tacitus's request.
Why it happened
- Vesuvius is one of the volcanoes created by the slow collision of the African and Eurasian plates, and it had been quiet for centuries while pressure built.
- Pompeii lay about ten kilometres from the crater, and the wind that day carried the ash cloud over the town.
- A long first phase of pumice fall gave time to flee; some who stayed died as roofs collapsed, and most of the rest were killed by the later surges.
What happened next
- Pompeii, Herculaneum and Stabiae were buried, and thousands died.
- Excavations from the 18th century gave Europeans a first detailed view of daily Roman life and fuelled the Neoclassical style.
- Rome moved on: after Titus came Domitian, Nerva and, in 98, Trajan, who took the empire to its greatest extent. Read the story →
Why it still matters
Volcanologists today speak of a Plinian eruption when a volcano throws up a tall column of ash, a term taken from Pliny the Younger's letter. Vesuvius last erupted in 1944, and Italy's civil protection plan now marks a red zone of 25 municipalities, including three districts of Naples, that would have to be evacuated before the next eruption.
Key people
- Pliny the Younger
- Roman lawyer and writer who watched the eruption and described it in two letters to Tacitus
- Pliny the Elder
- Naturalist and fleet commander who died at Stabiae trying to rescue people
- Titus
- Emperor in 79–81 CE, who organised relief for the stricken towns
- Giuseppe Fiorelli
- Archaeologist who developed the plaster-cast method at Pompeii in 1863
Key terms
- Pyroclastic flow
- A fast avalanche of hot gas, ash and rock from a volcano; the main killer at Pompeii and Herculaneum.
- Pumice
- Light, frothy volcanic rock that falls like hail from an eruption column.
- Herculaneum
- A smaller town near Vesuvius, buried under at least twenty metres of volcanic material.
- Plinian eruption
- A violent eruption with a tall column of ash, named after Pliny's description of this one.
Test yourself
How do we know what the eruption of Vesuvius looked like to people at the time?
- From a letter written by Pliny the Younger to Tacitus
- From an official report by the emperor Titus
- From a poem by the town's mayor
- From the diary of a Pompeian baker
Show the answer
From a letter written by Pliny the Younger to Tacitus. Pliny the Younger wrote two letters to the historian Tacitus about the eruption and the death of his uncle. No official report or diary from Pompeii survives.
The full lesson in the app ends with 5 questions like this one.
Connected stories
- Nero, the Great Fire and the Year of Four Emperors: Vespasian, the general who won the civil wars after Nero, founded the dynasty whose second emperor, Titus, ruled in 79.
- Hadrian and the Roman Peace: Pliny the Younger survived the eruption to govern Bithynia for Trajan, the emperor whose conquests Hadrian scaled back.
- The Black Death: Both were disasters that left unusually detailed accounts; but plague unfolded over years across a continent, the eruption in a day or two in one bay.
- The Founding of Rome: Legend and Evidence: Rome's own beginnings are known only through legend, but the burial of Pompeii preserved a town as it was on one day.
Frequently asked questions
Why was Pompeii destroyed by Vesuvius?
Vesuvius is one of the volcanoes created by the slow collision of the African and Eurasian plates, and it had been quiet for centuries while pressure built. Pompeii lay about ten kilometres from the crater, and the wind that day carried the ash cloud over the town. A long first phase of pumice fall gave time to flee; some who stayed died as roofs collapsed, and most of the rest were killed by the later surges.
What happened after the eruption of Vesuvius?
Pompeii, Herculaneum and Stabiae were buried, and thousands died. Excavations from the 18th century gave Europeans a first detailed view of daily Roman life and fuelled the Neoclassical style. Rome moved on: after Titus came Domitian, Nerva and, in 98, Trajan, who took the empire to its greatest extent.
How do we know what the eruption of Vesuvius looked like to people at the time?
From a letter written by Pliny the Younger to Tacitus. Pliny the Younger wrote two letters to the historian Tacitus about the eruption and the death of his uncle. No official report or diary from Pompeii survives.
What is the main primary source for “Pompeii: The Day Vesuvius Erupted”?
Pliny the Younger, Letters 6.16, to Tacitus (c. 106 CE). Translation by William Melmoth (first published 1746), revised by F. C. T. Bosanquet; in the Project Gutenberg edition this is letter LXV. Pliny describes what he saw from Misenum at seventeen and what he learned of his uncle's last hours, writing a quarter century later at Tacitus's request.
Sources
- Pliny the Younger, Letters 6.16 and 6.20, translated by William Melmoth, revised by F. C. T. Bosanquet
- Strabo, Geography 5.4.8
- Mary Beard, Pompeii: The Life of a Roman Town (2008)
- Alex Butterworth and Ray Laurence, Pompeii: The Living City (2005)
Images are credited under each picture. Paintings and photographs come from public collections via Wikimedia Commons; scenes with no surviving image are marked as illustrations.
