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Published October 18, 2019

We like to think that there’s solid earth beneath our feet, but that’s not really true. Just a few miles down, the mantle flows with the consistency of hot asphalt, and the crust itself moves in giant plates over the top. 

And in places, the hot molten magma beneath comes even closer to the surface. In some places, sometimes, it rises to the surface, and it can do so with a force that will be remembered throughout the ages.

The Campania region of Italy is extremely popular with tourists; beautiful landscapes, a rich cultural heritage, and a cornucopia of local culinary delights ensure that’s something to please everyone.

At its heart, the city of Naples is one of the oldest continuously inhabited areas in the world, and one of the most densely populated cities in Europe, with over three million people living within its metropolitan area.

And, looming beyond the city, stands Mount Vesuvius.

1,281 metres, or 4,203 feet, to the summit as measured in 2010, the mountain has a hump-backed appearance; it is, in effect, two mountains – Mount Somma being the second, and earlier, peak, dating back some seventeen thousand years. It is part of the Campanian arc, formed when the Eurasian and African tectonic plates collided.

There are several theories about the origin of the name “Vesuvius” – and they all share some similarities. It may come from Greek roots, meaning “unquenchable” or “hurling violence”; or it may come from Indo-European roots, meaning “one who lightens” or “hearth” – with similar roots to the Roman goddess of the hearth, Vesta. Whichever it may be, they all give hints about the nature of the mountain.

In Roman times, it was considered to be a divinity, connected to the god Jupiter, and also to the legend of Hercules. The historian Diodorus Siculus wrote;

“Heracles then moved on from the Tiber, and as he passed down the coast of what now bears the name of Italy he came to the Cumaean Plain. Here, the myths relate, there were men of outstanding strength the fame of whom had gone abroad for lawlessness and they were called Giants. This plain was called Phlegraean (“fiery”) from the mountain which of old spouted forth a huge fire as Aetna did in Sicily; at this time, however, the mountain is called Vesuvius and shows many signs of the fire which once raged in those ancient times.” 

It is, of course, a volcano; one which has erupted many times, including as recently as 1944. Its most famous eruption, however, remains the one which occurred in 79 AD.

Even though it occurred almost two thousand years ago, we have an eyewitness account of that eruption, courtesy of the Roman lawyer, author and magistrate Pliny the Younger.

Aged eighteen at the time, he was at Misenum, at the northwestern end of the Bay of Naples, living with his mother and his uncle, Pliny the Elder, who was the praefect in charge of the naval fleet there.

His account, however, was not written until about 25 years after the eruption; it was penned, across two letters, in response to a request from his friend Tacitus, a senator and historian, for an account of the death of Pliny the Elder.

“On the 24th of August, about one in the afternoon, my mother desired him to observe a cloud which appeared of a very unusual size and shape… he immediately arose and went out upon a rising ground from whence he might get a better sight of this very uncommon appearance.

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, for it shot up to a great height in the form of a very tall trunk, which spread itself out at the top into a sort of branches; occasioned, I imagine, either by a sudden gust of air that impelled it, the force of which decreased as it advanced upwards, or the cloud itself being pressed back again by its own weight, expanded in the manner I have mentioned; it appeared sometimes bright and sometimes dark and spotted, according as it was either more or less impregnated with earth and cinders.”

Pinus Pinea, the stone pine – the tree to which Pliny compared the ash column. Source: Wikimedia Commons.

While the younger Pliny stayed at home with his work, the elder took a ship with the intent of observing the eruption more closely. Before he left, he got a note from a lady whose villa was at the foot of Mount Vesuvius, asking for rescue by sea as she was otherwise cut off.

“He ordered the galleys to be put to sea, and went himself on board with an intention of assisting not only Rectina, but the several other towns which lay thickly strewn along that beautiful coast. Hastening then to the place from whence others fled with the utmost terror, he steered his course direct to the point of danger, and with so much calmness and presence of mind as to be able to make and dictate his observations upon the motion and all the phenomena of that dreadful scene.

He was now so close to the mountain that the cinders, which grew thicker and hotter the nearer he approached, fell into the ships, together with pumice-stones, and black pieces of burning rock: they were in danger too not only of being aground by the sudden retreat of the sea, but also from the vast fragments which rolled down from the mountain, and obstructed all the shore. Here he stopped to consider whether he should turn back again; to which the pilot advising him, “Fortune,” said he, “favours the brave; steer to where Pomponianus is.” “

Pomponianus was another Roman Senator; he was in the town of Stabiae, 16km or just under ten miles from Vesuvius. The direction of the wind didn’t allow him to put to sea to escape, but it did allow Pliny the Elder to sail in to join him.

The Bay of Naples, with mentioned locations labelled. Original photographed from the ISS. Source: Wikimedia Commons.

There, while “broad flames shone out in several places from Mount Vesuvius” Pliny set about soothing his friend’s nerves by ordering a bath and supper before retiring to rest – and apparently resting soundly, as his snores could be heard outside.

“The Eruption of Vesuvius as seen from Naples, October 1822” by George Julius Poulett Scrope . Source: Wikimedia Commons

“The court which led to his apartment being now almost filled with stones and ashes, if he had continued there any time longer, it would have been impossible for him to have made his way out. So he was awoke and got up, and went to Pomponianus and the rest of his company, who were feeling too anxious to think of going to bed. They consulted together whether it would be most prudent to trust to the houses, which now rocked from side to side with frequent and violent concussions as though shaken from their very foundations; or fly to the open fields, where the calcined stones and cinders, though light indeed, yet fell in large showers, and threatened destruction. In this choice of dangers they resolved for the fields: a resolution which, while the rest of the company were hurried into by their fears, my uncle embraced upon cool and deliberate consideration. They went out then, having pillows tied upon their heads with napkins; and this was their whole defence against the storm of stones that fell round them.

It was now day everywhere else, but there a deeper darkness prevailed than in the thickest night; which however was in some degree alleviated by torches and other lights of various kinds. They thought proper to go farther down upon the shore to see if they might safely put out to sea, but found the waves still running extremely high, and boisterous. There my uncle, laying himself down upon a sail cloth… called twice for some cold water, which he drank, when immediately the flames, preceded by a strong whiff of sulphur, dispersed the rest of the party, and obliged him to rise. He raised himself up with the assistance of two of his servants, and instantly fell down dead; suffocated, as I conjecture, by some gross and noxious vapour, having always had a weak throat, which was often inflamed. As soon as it was light again, which was not till the third day after this melancholy accident, his body was found entire, and without any marks of violence upon it, in the dress in which he fell, and looking more like a man asleep than dead.”

In the second letter, Pliny told Tacitus what he himself observed from his somewhat safer observation point at Misenum. He related a “trembling of the earth” which had been going on for many days, but which didn’t alarm them as it wasn’t particularly out of the ordinary. However, on that night it was so violent that it alarmed them, and other residents of the town, and persuaded them to attempt escape.

“Being at a convenient distance from the houses, we stood still, in the midst of a most dangerous and dreadful scene. The chariots, which we had ordered to be drawn out, were so agitated backwards and forwards, though upon the most level ground, that we could not keep them steady, even by supporting them with large stones. The sea seemed to roll back upon itself, and to be driven from its banks by the convulsive motion of the earth; it is certain at least the shore was considerably enlarged, and several sea animals were left upon it. On the other side, a black and dreadful cloud, broken with rapid, zigzag flashes, revealed behind it variously shaped masses of flame: these last were like sheet-lightning, but much larger… Soon afterwards, the cloud began to descend, and cover the sea. It had already surrounded and concealed the island of Capreae and the promontory of Misenum… The ashes now began to fall upon us, though in no great quantity. I looked back; a dense dark mist seemed to be following us, spreading itself over the country like a cloud. “Let us turn out of the high-road,” I said, “while we can still see, for fear that, should we fall in the road, we should be pressed to death in the dark, by the crowds that are following us.” We had scarcely sat down when night came upon us, not such as we have when the sky is cloudy, or when there is no moon, but that of a room when it is shut up, and all the lights put out. You might hear the shrieks of women, the screams of children, and the shouts of men; some calling for their children, others for their parents, others for their husbands, and seeking to recognise each other by the voices that replied; one lamenting his own fate, another that of his family; some wishing to die, from the very fear of dying; some lifting their hands to the gods; but the greater part convinced that there were now no gods at all, and that the final endless night of which we have heard had come upon the world… It now grew rather lighter, which we imagined to be rather the forerunner of an approaching burst of flames (as in truth it was) than the return of day: however, the fire fell at a distance from us: then again we were immersed in thick darkness, and a heavy shower of ashes rained upon us, which we were obliged every now and then to stand up to shake off, otherwise we should have been crushed and buried in the heap…

At last this dreadful darkness was dissipated by degrees, like a cloud or smoke; the real day returned, and even the sun shone out, though with a lurid light, like when an eclipse is coming on. Every object that presented itself to our eyes (which were extremely weakened) seemed changed, being covered deep with ashes as if with snow.”

The Last Day of Pompeii (1827–1833) – Karl Briullov, Source: Wikimedia Commons

Although it was written some time after the events, Pliny’s account is thought to be generally accurate. There are, however, still some points of contention, most notably the date. Pliny says that the eruption occurred on the 24th of August, and this is the traditionally accepted date. However, archaeologists have noted that some of the evidence doesn’t fit. Victims have been found wearing clothes that would be too warm for the summer, and evidence shows that braziers had been lit. Fruits and vegetables on sale also indicate that it was later in the year; summer fruits were in dried or preserved forms, and autumnal fruits like the pomegranate were available. An inscription was found in 2018, written in charcoal, giving a date equivalent to the 17th of October in the modern calendar. It seems unlikely that it meant October of 78 AD, as the charcoal would have been rubbed away in that time – so it must have been at least October when the eruption occurred. In addition, the direction in which the cloud from the volcano travelled is more typical of autumn weather than of summer.

This discrepancy could be due to the way Roman dates were given – they counted forward to the next Kalends, Ides or Nones of the month, so the charcoal inscription gives the date as 16 days before the Kalends of November – and/or a mistake in early translations which has persisted. All of the existing translations from medieval times forwards give the August date, but today it seems more likely to have been towards the very end of October or beginning of November.

Another question sometimes raised is how Pliny the Elder could have received Rectina’s note asking for help so soon after the explosion had been sighted. The answer is that smaller eruptions and earthquakes would already have been shaking the area right at the mountain’s roots, not large enough to be seen from Misenum but certainly enough to frighten the lady. Considering that her messenger got through, it seems that she would have been better off going with him.

There is another Roman account of the 79 AD eruption, written by Cassius Dio in his “Roman History.” He lived from about 155 AD to about 235 AD, meaning the eruption happened 76 years before he was even born, and his account therefore has to be at least third- or fourth hand. He described it as a great fire which, “suddenly flared up at the very end of the summer.”

“…fearful droughts and sudden and violent earthquakes occurred, so that the whole plain round about seethed and the summits leaped into the air. There were frequent rumblings, some of them subterranean, that resembled thunder, and some on the surface, that sounded like bellowings; the sea also joined in the roar and the sky re-echoed it. Then suddenly a portentous crash was heard, as if the mountains were tumbling in ruins; and first huge stones were hurled aloft, rising as high as the very summits, then came a great quantity of fire and endless smoke, so that the whole atmosphere was obscured and the sun was entirely hidden, as if eclipsed. Thus day was turned into night and light into darkness.

Some thought that the Giants were rising again in revolt (for at this time also many of their forms could be discerned in the smoke and, moreover, a sound as of trumpets was heard), while others believed that the whole universe was being resolved into chaos or fire. Therefore they fled, some from the houses into the streets, others from outside into the houses, now from the sea to the land and now from the land to the sea; for in their excitement they regarded any place where they were not as safer than where they were. While this was going on, an inconceivable quantity of ashes was blown out, which covered both sea and land and filled all the air. It wrought much injury of various kinds, as chance befell, to men and farms and cattle, and in particular it destroyed all fish and birds. Furthermore, it buried two entire cities, Herculaneum and Pompeii, the latter place while its populace was seated in the theatre. Indeed, the amount of dust, taken all together, was so great that some of it reached Africa and Syria and Egypt, and it also reached Rome, filling the air overhead and darkening the sun.”

According to modern volcanologists who have studied the mountain, the eruption had two phases. The first was what we now call the Plinian eruption, thanks to Pliny’s detailed description – the rising column of ash and pumice which spread out and rained down upon the area. This would have lasted about eighteen to twenty hours. Then, there would have been a second phase, which is now described as a Peléan eruption after the 1902 Mount Pelée eruption. This is characterised by pyroclastic flows; massive, roiling, cloud-like surges of hot gases and volcanic debris which flow down the mountain at inescapable speeds of up to 700 km/h or 450 mph.  

The eruption would have alternated between these two phases six times.

It’s thought that first, the column threw ash and pumice down on Pompeii, which was southeast, downwind of the volcano; then the first pyroclastic flows surged down into Herculaneum, 7km or 4 miles to the west of the mountain’s crater. The fourth and fifth surges are thought to be those which destroyed Pompeii; the last, and largest, the one which cut Pliny the Elder off from escape.

Studies have shown that the pumice stones falling on Pompeii in that first instance were so hot that they heated roof tiles to between 120 and 140 celsius – 250 – 280 Fahrenheit. Anyone who had not escaped at that point was already doomed.

The temperatures of the pyroclastic flows would have ranged from 180 Celsius (360 fahrenheit) up to 600 Celsius which is 1,112 fahrenheit. Without extensive protective gear, those temperatures are basically fatal.

The volcanic debris that was thus carried down from Vesuvius buried both cities; Pompeii was buried some 4 metres or 13 feet down, and Herculaneum disappeared under between 9 and 21 metres – 30 to 69 feet – of ash and rock.

Although both Pompeii and Herculaneum were buried deep, they would not remain lost forever.

Sometime between 1592 and 1600, construction of a canal in the area brought a number of artefacts to light, including paintings, inscriptions and frescoes – but their significance was not recognised, and they were covered up again. It has been theorised that this was because they’d found some of the ruder frescoes found in the city, and they were reburied because prevailing attitudes of the time deemed them distasteful.

Pompeii and Vesuvius, pictured around 1900. Source: Wikimedia Commons

In 1738, while workmen were digging foundations for a summer palace for the King of Naples, they stumbled upon the remains of Herculaneum; this led to new excavations in the area of Pompeii. In 1763, the discovery of an inscription reading, in part, “Rei Publicae Pompeianorum” told the diggers that they had, indeed, found Pompeii.

The style of these early excavations would probably make modern archaeologists despair. Rather than working to uncover the city carefully and scientifically, they were often simply looking for antiquities which could be displayed to reinforce the area’s reputation.

However, eventually it became more orderly. In 1836, the archaeologist Giuseppe Fiorelli was put in charge of the excavations. 

It was he who realised that certain voids in the compacted ashes indicated the former location of organic remains. He developed a technique of pumping in plaster to fill the void, and then chipping away the ashes outside to reveal exactly what the ashes had enveloped.

He revealed the victims of Vesuvius; men, women, children, even animals, frozen at the very moment of their deaths. Although they cannot speak, these models of their bodies still tell their tales very eloquently. In some cases, they are so detailed that you can clearly see the expressions on their faces and the style of their hair. Bodies have been found in the act of embracing each other; a woman was found holding a child, a man sitting with his head in his hands, a dog trying to chew through its leash so it can run.

Although it was originally believed that most of the victims would have suffocated on the ashes, more recent studies show that they were more likely heated to death in a flash. This would explain some of the very lifelike positions they were found in, and the fact that many had their arms raised as if to fight – this is called a “pugilistic attitude” and was caused by the rapid heating, dehydrating and contracting of their muscles. The falling ashes then quickly enveloped their bodies and hardened around them; their soft tissues decayed within this shell, leaving a human-shaped hole with perhaps some skeletal remains inside.

The deaths of those at Herculaneum was a little different to those at Pompeii; there, the heat was greater, and the victims were carbonised, leaving only their skeletons behind. Comparative studies indicate that victims in Pompeii probably suffered temperatures of 250-300 Celsius (482 – 572 fahrenheit) while those in Herculaneum suffered temperatures of around 500 Celsius – 932 fahrenheit. At other sites in the area, such as Oplontis, it was even higher – 600 celsius, 1,112 fahrenheit.

Oplontis, lying between Pompeii and Herculaneum, was the site of a villa where 54 skeletons were found in one room. At one side, near the exit, the victims were found with items indicating wealth, such as coins and jewellery; at the back of the room, the victims had nothing. Perhaps they were slaves and servants, indicating the class separation of Roman society – or perhaps they had simply been too scared to gather their things before running. Whatever the truth, it obviously made no difference – poor and rich alike died at the same instant.

Many of the skeletons at Herculaneum have been found near the shore – on the beach or inside boathouses. However, there was no evidence of any boats found, meaning that those unfortunate people had no escape. The buildings gave them no protection from the immense temperatures of the pyroclastic flow. Evidence seems to show that Herculaneum was a more prosperous area than Pompeii, and again, victims have been found with luxurious items on them. One, a skeleton known as the Ring Lady, had two rings, one emerald and one ruby, on her left hand, as well as gold bracelets and gold earrings.

Today, tourists flock to Pompeii, Herculaneum and Vesuvius itself; the area around the mountain is a National Park, open to tourists with road access to within 200metres (660 feet) vertically of the summit. From there, you can follow a walkway to the crater.

However, it is still very much an active volcano.

Since 79 AD, it has erupted about three dozen times. In 1631, around three thousand people were killed and many villages buried; in 1906, more than a hundred people were killed, and a record-breaking amount of lava ejected – the impact was so severe that the 1908 Olympics had to be moved from Rome to London, as all the funds had been diverted to help Naples recover.

The most recent eruption was in 1944, when several villages were destroyed, 26 Italians were killed and nearly 12,000 displaced, while volcanic debris inflicted serious damage on the aircraft of the United States Air Force 340th Bombardment Group, then based at Pompeii airfield.

The eruption of 1944. Source: Wikipedia.

But these were not all violent, Plinian eruptions; and none since have been on the scale of the 79 AD eruption. So the question for volcanologists is, has the worst passed – or is there still a danger that Vesuvius will once more awaken like a huge, angry dragon?

That could depend on how long it stays quiet. It’s thought that the longer the magma stays in the chamber beneath the volcano, the more explosive the eventual eruption is likely to be. That means, if it happens next year, it could be pretty bad; if it doesn’t happen for another fifty, or a hundred and fifty years, it could be worse.

Emergency plans made by the government currently assume that the next eruption will be, in a worst case scenario, on a similar scale to the 1631 eruption. That was ranked on the Volcanic Explosivity Index at a 4, similar to the 1902 Mount Pelée eruption; the 79 AD eruption is ranked higher at a 5. 

The plans would call for the evacuation of about 800,000 people – a process which is expected to take up to seven days. These evacuees would be those living in the Zona Rossa, or Red Zone, an area first defined in 2001 and further refined in 2013, which is at the highest risk from pyroclastic flows, lava or ash falls. The government is also working to reduce the number of people living in this area.

To ensure that they actually have enough notice to put that plan into action, Vesuvius is under observation by the Vesuvius Observatory, first established in 1841. Seismicity, soil deformation, and gas emissions from the soil and from fumaroles are all constantly monitored. In addition, periodic checks are made, taking a range of other measurements to ensure that the scientists can maintain an accurate view of the volcano’s status.

Based on this, the emergency plans assume that they’ll have between two weeks and 20 days’ notice of the next Big One. Unfortunately that brings with it another dilemma – when exactly to put an evacuation into motion. Too late, and people might die; too soon, and you risk moving hundreds of thousands of people over a false alarm.

But for now, the mountain is quiet, so if you’re currently planning a holiday in Naples, chances are, it’ll be fine. Just don’t take it entirely for granted.

Thanks this episode go to:

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Sources, References and Further Reading

The Legend of Hercules – Diodorus Siculus

Pliny the Younger’s Letters– Project Gutenberg

The 79 AD eruption of Somma: The relationship between the date of the eruption and the Southeast Tephra dispersion – ResearchGate

Pompeii: Vesuvius eruption may have been later than thought – BBC News

Roman History – Cassius Dio

The Destruction and Rediscovery of a Roman City

In the Shadow of the Volcano – Volcanologist Bill McGuire on the dangers of Vesuvius – The Guardian

Vesuvius – Current Status – Vesuvius Observatory



Archaeology and the Dead III: The Day the World Exploded: Pompeii and Herculaneum – Catherine Gaither

The Eruption of Vesuvius: The Deadly Disaster of Pompeii (History) – 50 Minutes

Burning Mountain: Encounters With Mount Vesuvius – Jon Miller:

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