Countdown to disaster: a timeline of the last hours of Pompeii

First day of the eruption

10:00

Those minor tremors are still being felt across Pompeii, and have been for the last four days. Yet its citizens still appear to be unconcerned. No one is heeding what will later be interpreted as warning signs. The markets are still busy, the trade is still brisk. It’s another typical morning without note. But then comes lunchtime...

13:00

Shortly after noon, as residents are stopping to refuel, Mount Vesuvius roars into life. Inside the mountain, the pressure caused by molten rock – the origin of the tremors felt over the past few days – has grown to such a point that there’s no way back. It has to escape, and so Vesuvius erupts for the first time in several centuries. A huge column of volcanic rock and ash is sent soaring as high as 10 miles into the air. What had been a typically cloudless summer’s day is very quickly extinguished by a cloud of volcanic debris, spreading swiftly to block out the early afternoon sun. It is the darkest of clouds for what will be the darkest of days for Pompeii and its residents.

The explosion is unfathomably violent, unfathomably large. Each and every second, around 1.5 million tonnes of debris is being expelled from the depths of the mountain’s belly. At the same time, the vast – and growing – cloud is being pushed the short distance between Vesuvius and Pompeii by southeasterly winds.

Across the Bay of Naples, in the port of Misenum, a 17-year-old boy is watching the catastrophic events unfold. The nephew of Pliny the Elder – the naturalist, philosopher and author of the 37-volume Naturalis Historia – the teenager will later produce an eyewitness account of the tragic events, which will become the strongest written testimony of this fateful day. In Misenum, he watches the contents of the eruption fill the sky. He will note that, above the volcano, the cloud resembled an umbrella pine tree, “raised high on a kind of very tall trunk and spread out into branches”.

Pliny the Younger is currently staying with his namesake uncle who, as the serving admiral of Rome’s navy, instinctively decides to set sail across the bay. Accompanied by several oar-driven warships, the intention is presumably to execute some kind of evacuation of Pompeii’s population. Even if he were able to land close to the city (which he is unable to do as debris falls from the sky into the sea, creating dangerous floating islands in the shallow water), such is the scale of the disaster that it would be the tiniest, most piecemeal operation.

16:00

The cloud has travelled the five miles towards Pompeii and is now raining tens of thousands of tonnes of pumice down onto its citizens. Some have tried to escape – whether into the countryside or by taking to the sea – but so rapid and so heavy is the deluge that there’s no real hope for the population who remain inside the city. They are trapped. Many seek shelter in their homes – hoping to be protected, hoping to survive – but the sheer weight of the accumulated pumice is causing entire houses to collapse.

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For those local residents fortunate to avoid a direct hit, their fate is already determined by another development. Very soon the city will be smothered by thick ash, concealing everything and everyone. Over the next 24 hours, the ash and debris will settle on the city as much as three metres deep. All the while, the eruption continues throughout the afternoon and evening, and into the night. At its peak, the surge from the massive volcano reaches as high as 20 miles into the sky.

Second day of the eruption

01:00

After 12 hours of firing its huge plume of debris upwards, the gases inside Vesuvius begin to weaken, to lose their intensity. This is not necessarily good news. This is not the end of the disaster. The volcano still has plenty of its innards to expel. It will just do so less spectacularly now – less spectacular but even more deadly. Pyroclastic flows – super-heated clouds of ash, gases and volcanic debris – surge down its slopes, engulfing all in their path. Having been saved by the prevailing winds that has allowed it to largely avoid the airborne debris of the past 12 hours, the coastal city of Herculaneum, located to the west of Vesuvius, doesn’t manage to escape this time.

06:00

At daybreak, with the volume of ash falling on the city lessening, those Pompeiians who, by fortune or fate, have survived begin to take stock of what’s happened to their neighbourhoods, to their friends, to their families. It’s comparatively quiet now. They believe that the horrific events have dissipated, that Vesuvius has uttered its last roar. It’s now a grim search for the bodies of the casualties.

On the beach at Stabiae, a port a few miles to the south of Pompeii, a notable casualty will be revealed the following morning. Having sheltered in the town for the first night of the eruption, the body of Pliny the Elder is discovered. One school of thought is that he has died by asphyxiation, caused by inhaling the volcanic ash. But the ashfall is less significant in Stabiae than elsewhere; it may be that he has suffered an asthma attack or cardiac arrest.

07:30

The willingness of those surviving Pompeiians to believe that Vesuvius has now fallen silent again proves to be misplaced. The volcano belches out its fourth pyroclastic surge, which charges towards the city at the scarcely believable speed of around 200 miles per hour. Across the Bay of Naples, the teenage Pliny – who will soon abandon Misenum with his mother – is observing from a distance. “It was daylight now elsewhere in the world,” he would later write, “but there the darkness was darker and thicker than any night.”

In among the darkness, he reports “zigzag flashes” and “variously shaped masses of flame”. As the surges power their way towards the sea, there’s the very likely possibility of a tsunami affecting the local waters. It’s an apocalyptic sight for the despondent teenager. “I derived some poor consolation in my mortal lot from the belief that the whole world was dying with me and I with it.”

None of the residents who remain have any hope of surviving the heat and intensity of the flow, its temperature measuring several hundred degrees centigrade. Another pyroclastic surge soon follows and completely submerges the city, trapping Pompeii in situ. No more will Pompeiians go about their day-to-day business. No more will this city bustle. Its streets, its buildings, its people will now sleep forever.

Nige Tassell is a journalist specialising in history

This article was first published in the October 2022 issue of BBC History Revealed