Mount Vesuvius

Mount Vesuvius is a famous stratovolcano in southern Italy, near the city of Naples. It is best known for its catastrophic eruption in 79 AD that destroyed the Roman cities of Pompeii and Herculaneum, killing thousands of people and preserving their bodies, their houses and their possessions under metres of ash. Vesuvius is one of the most studied volcanoes in the world. It is also still active and is considered one of the most dangerous volcanoes on the planet today, with approximately 3 million people living within 30 km of it.

  • Height1,281 mStratovolcano
  • Famous eruption79 ADBuried Pompeii and Herculaneum
  • Last big eruption1944During World War II
  • TypeStratovolcano (composite)On a subduction zone
  • People within 30 kmApproximately 3 millionOne of the most populated volcanoes
  • VEI of 79 AD eruption5"Plinian" style

The 79 AD eruption

On the morning of 24 August 79 AD (or possibly autumn that year, the exact date is debated), Mount Vesuvius produced one of the most famous eruptions in history. After centuries of being dormant (most local Romans did not even realise it was a volcano), Vesuvius suddenly began throwing a giant ash column kilometres into the sky.

The eruption lasted about 24 hours and went through several phases.

  1. The initial Plinian phase: a 30+ km tall ash column rained ash and pumice on the city of Pompeii to the south.
  2. Pyroclastic flows: superheated avalanches of ash, gas and rock poured down the mountain at hurricane speeds, hitting first Herculaneum (closer to the volcano) and then Pompeii.
  3. Final ash fall: the eruption gradually died down, leaving both cities buried under several metres of ash and pumice.

An estimated 1,500 to 3,000 people died directly from the eruption (out of total city populations of approximately 16,000 in Pompeii and 5,000 in Herculaneum). Many were killed in seconds by the heat of the pyroclastic flows. Others died from suffocation in the ash or were crushed by collapsing roofs.

The eyewitness: Pliny the Younger

We have a detailed eyewitness account of the eruption from a Roman teenager named Pliny the Younger. His uncle, Pliny the Elder, was a Roman admiral who sailed out to try to rescue people from the coast (and died from gas inhalation in the attempt). The younger Pliny wrote two letters to the historian Tacitus describing what he had seen from across the Bay of Naples. His descriptions are so precise that scientists named this style of eruption "Plinian" in his honour. His letters are still standard reading in volcanology courses today.

What was preserved

The ash and pumice that buried Pompeii and Herculaneum sealed in everything below them: buildings, streets, frescoes, mosaics, gardens, even loaves of bread in ovens. The cities were essentially time capsules of Roman life, preserved untouched for nearly 1,700 years.

Modern archaeologists have uncovered:

  • Entire streets, houses, shops, taverns and public buildings.
  • Beautiful wall paintings and floor mosaics in their original positions.
  • Graffiti scratched into walls, including jokes, election posters and rude humour.
  • The carbonised remains of food, scrolls, and even loaves of bread.
  • Casts of the bodies of victims, made by pouring plaster into the hollow spaces left when the bodies decayed inside the hardened ash.

Pompeii is now one of the most visited archaeological sites in the world, with over 2.5 million tourists per year.

Fact The plaster casts of Pompeii victims are some of the most haunting archaeological objects in the world. When the volcanic ash hardened around the dying victims, their bodies eventually decayed leaving hollow shapes inside the rock. In 1863, an Italian archaeologist called Giuseppe Fiorelli invented a technique of pouring liquid plaster into these hollows. When the plaster set and the rock was carefully removed, perfect casts of the victims emerged: men, women, children and even dogs, frozen in their final moments.

Other eruptions of Vesuvius

Vesuvius has erupted many times before and since 79 AD. Notable eruptions include:

  • 1631: a major eruption that killed approximately 4,000 people.
  • 1872: small lava flows damaged villages on the slopes.
  • 1906: a powerful eruption that killed approximately 100 people.
  • 1944: the most recent eruption, during World War II. Destroyed several Allied aircraft on the ground.

Since 1944, Vesuvius has been quiet. But "quiet" does not mean "extinct". The longer Vesuvius stays quiet, the more pressure can build up in its magma chamber, and the more violent the next eruption is likely to be.

Did you know? Approximately 3 million people live in the metropolitan area of Naples, much of it inside the danger zone for the next Vesuvius eruption. The Italian government has detailed evacuation plans (it would take 72 hours to move everyone), but many people are reluctant to leave their homes. Vesuvius is one of the world's most-monitored volcanoes precisely because so many lives depend on getting the warning right.
Deeper dive: why Pompeii's preservation is unique in the world

Many ancient cities have been excavated, but none has been preserved quite like Pompeii. The exceptional preservation comes from the unusual way the city was buried.

Most ancient cities decay and are recycled by their inhabitants over time: stones get reused for new buildings, valuables get carried away, wooden buildings rot and collapse. Most archaeology is about working out what an unusually well-preserved foundation suggests about a building, then guessing what the building above it looked like.

Pompeii was different. The eruption happened so suddenly that the entire living city was buried under approximately 4 to 6 metres of pumice and ash within 24 hours, with no time for evacuation or for looters to come back later. The ash quickly set, sealing everything in place. With no rain and no humans to disturb it, the city stayed essentially undisturbed for 1,700 years.

When excavation finally began in the 1700s, archaeologists found:

  • Complete buildings with their roofs intact.
  • Bright fresco paintings still on the walls.
  • Floor mosaics in their original positions.
  • Wooden doors, shutters and shelves carbonised but preserved.
  • Pots, pans, cutlery, jewellery, lamps and toys exactly where the residents left them.
  • Graffiti on walls, including jokes, gossip, election campaign messages and even crude drawings.

The result is the most detailed window into ancient daily life that exists anywhere in the world. Walking through Pompeii today, you can see exactly what the Roman empire looked like at street level: the bakery, the brothel, the gladiator school, the wine bar with menus painted on the wall. No other archaeological site comes close. The tragedy that killed thousands of Romans in 79 AD has given humanity one of its greatest cultural treasures.

For more, see types of volcano, volcanic eruptions and the Ring of Fire.