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Deconstructing history: the eruption of Mount Vesuvius

Did the eruption bury Pompeii in August or October?

… 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… [many were] 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.
~Pliny the Younger

Pliny theYounger (Gaius Plinius Caecilius Secundus, 61-113 CE) wrote those words almost 30 years after Mount Vesuvius buried the Roman city of Pompeii in 79 CE.

The destruction of Pompeii and the nearby coastal town of Herculaneum is undoubtedly history’s most storied natural disaster. The ancient Roman cities were buried under layers of volcanic rock and ash—frozen in time—until their rediscovery and exploration in the 18th century.

Located a few miles from the Bay of Naples, Pompeii was home to about 20,000 people. It was situated in a fertile agricultural area, fertile because the neighboring volcano had scoured the area about 2,000 years earlier.

His uncle, Pliny the Elder (Gaius Plinius Secundus, 23/24 – 79 CE) was commander of the Roman fleet at Misenum (up the coast from Pompeii). Pliny the Elder set sail on a rescue mission after the family had spotted the eruption.

How do we know the exact date — 24 August 79 CE — that Mount Vesuvius erupted, a date almost 2,000 years in our past?

We have those details in two letters that Pliny theYounger wrote to the Roman senator and historian Tacitus. Letters copied by hand over the centuries. And then translated (see three ‘modern’ translations).

In his first letter, which details the death of his uncle, Pliny theYounger wrote (1909 translation):

On the 24th of August, about one in the afternoon, my mother desired [Pliny the Elder] to observe a cloud which appeared of a very unusual size and shape.

The ninth-century manuscript known as the Codex Laurentianus Mediceus “dates the eruption to the ‘ninth day before the kalends [first] of September’ (in Latin, nonum kal. Septembres)–in other words, August 24… This date for the eruption has become canonical.”

Other versions suggest a different date, such as 24 October.

Archeologists have found pomegranates and walnuts in the ruins, fruits of autumn. They have also found an ancient sauce from fish “most plentiful in summer.”

Atmospheric studies, meanwhile, have suggested that the fallout pattern of volcanic ash reflects high-altitude south-easterly winds, which today are prevalent in the region in autumn. Wind patterns may, however, have changed in the almost two thousand years since the eruption.

In 2018, Italian archeologists found an inscription that appears to date the eruption in October, not August, 79 CE.

The inscription discovered in the new excavations is nothing more than a scrawl in charcoal, likely made by a worker renovating a home.

But it is dated to 16 days before the “calends” of November in the old Roman calendar style – which is 17 October in our modern dating method.

“Since it was done in fragile and evanescent charcoal, which could not have been able to last long, it is highly probable that it can be dated to the October of AD 79,” the archaeology team said in a statement.


To most historians and archeologists, a difference of two months might elicit a shrug.

However, for bioarchaeologists, a difference that crosses seasons changes the nature of their “hypotheses about and interpreting data from the human skeletal remains.”

[T]hese Bay of Naples sites – Pompeii, Herculaneum, Oplontis – are catastrophic mortality sites rather than true cemeteries. As such, they’re incredibly important for understanding both demography and disease ecology in the early Roman Empire.

Although discovered late in the 16th century, it was the mid-18th century before archeologists began excavations and learned that the ruins were of Pompeii.

“Pompeii as an archaeological site is the longest continually excavated site in the world,” Steven Ellis, co-director of the Pompeii Archaeological Research Project: Porta Stabia, told National Geographic.

At Pompeii, archeologists can “trace the history of Italic and Roman domestic architecture for at least four centuries. The earliest houses date from the first Samnite period (4th–3rd century BCE).” Houses can provide insight into “social, economic, religious, and political life.”

The excavations have become a tourist magnet. Bustling crowds and the excitement of a peek at such an ancient culture can mask risks. Vesuvius is the only active volcano in mainland Europe and one of the most dangerous volcanoes on the planet.

About 3,800 years ago (Bronze Age), after a massive eruption, lava and ash from Vesuvius smothered the area of present-day Naples with deposits that are four meters thick.

With the size of any future eruption in doubt, and a public more concerned about day-to-day problems such as traffic and crime, mitigating the hazard of Vesuvius is an enormous task shared by researchers and the civil authorities.

Bioarchaeology is a recent field of study focused on an area of the world lost for centuries, a field where a two-month difference matters.

Officials on the ground in Italy have more pressing concerns. Will the next eruption be minor, like the one in 1944, or major like the one in 79 CE? And how do officials develop emergency plans for the impossible: quickly evacuating Naples, a city of more than 3 million people?

Mount Vesuvius map
Map represents direction and distance of ash and debris ejected during the eruption of Mount Vesuvius in 79AD. Wikimedia, edited to add modern Naples.

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📷 Wikimedia Commons
Eruption of Vesuvius, Pierre-Henri de Valenciennes, 1813.
Daily posts, 2022-2023

By Kathy E. Gill

Digital evangelist, speaker, writer, educator. Transplanted Southerner; teach newbies to ride motorcycles! @kegill

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