What happened in Pompeii in 79 AD

Short answer: in 79 AD Vesuvius erupted for about a day. First a column of pumice rained on Pompeii for many hours and brought roofs down; then, early the next morning, avalanches of hot gas and ash swept through the streets and killed everyone still there. The city stayed buried under several metres of volcanic debris for almost 1,700 years.

Before: a city that was still rebuilding

Pompeii was a prosperous town of perhaps ten to twelve thousand people near the Bay of Naples. Nobody knew Vesuvius was a volcano: it was a green mountain covered in vineyards. In 62 or 63 AD a strong earthquake damaged the town, and when the eruption came seventeen years later, many buildings were still under repair — you can see unfinished work in several houses and in the Forum.

Day one: the pumice fall

Around midday the mountain blew open. Pliny the Younger, watching from Misenum across the bay, compared the cloud to an umbrella pine: a tall trunk that spread out at the top. The wind carried it southeast, straight over Pompeii.

For the rest of the day and through the night, light grey and white pumice fell on the town. It was not immediately lethal, but it piled up to well over a metre, the weight collapsed roofs, and the sky went dark. Many people fled in these hours, which is why the number of dead found is far below the population. Those who stayed sheltered indoors or tried to leave later.

Day two: the surges

During the night the eruption column began to collapse. Its material came down the slopes as pyroclastic currents: fast, ground-hugging avalanches of gas, ash and rock at several hundred degrees. Herculaneum, closer to the volcano, was hit first, after midnight. Pompeii was reached early in the morning. Anyone still in the town — in houses, in the streets, at the gates — died within minutes, mostly from heat and from breathing the ash.

Further currents and ash falls followed, and by the end the town lay under several metres of deposit. Only the tops of the tallest walls stuck out.

What Pliny saw

Almost everything we know from an eyewitness comes from two letters Pliny the Younger wrote to the historian Tacitus about 25 years later. His uncle, Pliny the Elder, commanded the Roman fleet at Misenum; he sailed across the bay to rescue friends, landed at Stabiae and died on the beach there. The nephew, 17 at the time, stayed behind and described the darkness, the earthquakes and the crowds fleeing Misenum.

August or October?

The traditional date, 24 August, comes from the manuscripts of Pliny’s letter, which were copied many times. Archaeologists had long noticed autumn clues: pomegranates and other late-season fruit, braziers in use, heavier clothing on some victims. In 2018 a charcoal inscription found in a house in Regio V gave a date equivalent to 17 October — written, it seems, shortly before the eruption. Many researchers now favour a date in autumn, often 24 October, but the question is not closed.

How Pompeii was found again

The town was never completely forgotten, but its location was. Excavations began under the Bourbon kings of Naples, at Herculaneum in 1738 and at Pompeii in 1748; only in 1763 did an inscription confirm the site was Pompeii. Around two thirds of the city has been dug since. In the 1860s Giuseppe Fiorelli introduced systematic excavation and the plaster casts of the victims. Digging continues today.

Is Vesuvius still active?

Yes. It has erupted many times since 79 AD, most violently in 1631, and last in 1944. It is one of the most closely monitored volcanoes in the world; the observatory on its slopes, founded in 1841, was the first of its kind. You can walk to the crater rim — the same day as Pompeii, if you plan it.

Updated 2026-10-27