How Vesuvius destroyed Pompeii

Vesuvius Pompeii eruption
A map showing the spread of the ash clouds

At noon on 24 August in 79 CE, Mount Vesuvius erupted near the bay of Naples in southern Italy in what would become one of the most devastating natural disasters of ancient times.

The nearby cities of Pompeii and Herculaneum were completely buried by the ash and pyroclasts that spewed from the volcano, helping to preserve them in extraordinary detail. We also have detailed information about the eruption itself thanks to Pliny the Younger, who wrote two letters detailing what he saw from his mother’s house in Cape Misenum. His famous description of the plume as “shaped like a pine” caused this type of eruption to be named a Plinian eruption.

10am, 24 August, 79 CE

For four days prior to the eruption, small earthquakes are felt throughout the city of Pompeii. As this happens every year without consequence, the inhabitants think nothing of it. Many of them congregate in the public forum, the political, religious and commercial heart of the city.

1pm, 24 August, 79 CE

After several small explosions, Vesuvius erupts, sending a tall cloud of lava and ash over 20km (12mi) into the sky. The cloud blocks out the Sun, plunging everything into darkness, and violent tremors cause buildings to collapse. People run toward the coast in search of rescue, but rough seas make escape by water impossible.

9pm, 24 August, 79 CE

Hot ash and lumps of volcanic rock rain down over Pompeii, which is downwind from the volcano. People become trapped in their houses as debris blocks the doors, and roofs begin to collapse from the weight of the ash and rock. Many people are also killed by the emissions of sulphuric gases.

12am, 25 August, 79 CE

The ash cloud reaches its maximum height of 30km (19mi) and then collapses, sending a pyroclastic surge of hot gas and rock down the volcano’s northwest slope toward Herculaneum. Moving up to 700km/h (435mph) and with temperatures up to 400°C (752°F), the surge instantly kills everyone it touches.

6am, 25 August, 79 CE

As dawn breaks, the cloud collapses for the last time, sending another pyroclastic surge toward Pompeii that kills everyone in its path. By the time the eruption is over, Pompeii is buried underneath 5m (16ft) of volcanic material, while Herculaneum is buried under 20m (66ft).

Vesuvius Pompeii eruption
How the eruption unfolded

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