8:00 AM | On this date in 79 A.D., Mount Vesuvius erupted and Pompeii, Italy was changed forever

Pompeii today with Mount Vesuvius in the background

Overview
It was shortly after noon on August 24th in the year 79 A.D. and Mount Vesuvius sent a tall cloud of steam and ash high up into the atmosphere.  The ancient Roman town of Pompeii near modern day Naples was soon covered in complete darkness and the thickness of the falling debris increased by about 6 to 8 inches per hour.  The rocks which comprised the debris were up to 3 inches in diameter and fell with a speed of up to 100 miles/hour.  This first phase of the eruption led to casualties primarily caused by roof collapses. After 12 hours of continuous explosive activity, the second phase of the eruption began and it was characterized by substantial flow of lava down the sloping Mount Vesuvius and this caused additional deaths and destruction.  In fact, the eruption of Mount Vesuvius spewed 1.5 million tons of lava per second into Pompeii and surrounding towns.  In a short period of time, two thousand people were killed, the small towns of Herculaneum, Oplonti and Stabiae were destroyed, and Pompeii was changed forever.  

Life in Pompeii in Roman times
Ever since the ancient Greeks settled in the area in the 8th century B.C., the region around Mount Vesuvius and the Bay of Naples attracted wealthy vacationers who wanted to soak up the sun and enjoy the scenery. By the turn of the first century A.D., the town of Pompeii, located about five miles from the mountain, was a flourishing resort for Rome’s most distinguished citizens. Elegant houses and elaborate villas lined the paved streets and there was sophisticated plumbing. Tourists, townspeople and slaves bustled in and out of small factories and artisans’ shops, taverns and cafes and bathhouses. People gathered in the 20,000-seat arena and lounged in the open-air squares and marketplaces. On the eve of that fateful eruption in 79 A.D., scholars estimate that there were about 20,000 people living in Pompeii and the surrounding region.

Pompeii and other cities affected by the eruption of Mount Vesuvius. The black cloud represents the general distribution of ash and cinder. Modern coast lines are shown.

The eruption and weather’s impact
While there was a powerful earthquake in the same region some seventeen years beforehand, in the days preceding the massive eruption on Mount Vesuvius there were generally only minor earthquakes and this was not too unusual for the residents of Pompeii who had no idea what was about to happen.  In fact, the people of Pompeii didn’t really even know that Mount Vesuvius was a volcano as it hadn’t erupted in 1800 years.  Then, shortly after noon on August 24th in the year 79 A.D., a major eruption sent a plume of ashes, pumice and other rocks, and scorching-hot volcanic gases so high into the sky that people could see it for hundreds of miles around.  Ironically, this eruption took place the day after the Roman holiday of Vulcanalia which is dedicated to the god of fire including fire from volcanoes.  This outpouring of ash more than 20 miles high into the upper atmosphere continued unabated for the next 12 hours and choking ash rained down on the towns in the surrounding country side blocking doors and collapsing roofs.  Had the eruption taken place on any other day, the people of Pompeii might have stood a better chance of escape. Usually the wind blows in a southwesterly direction during the summer season in this part of the Italian Peninsula and this would have blown the column of ash away from Pompeii. However, on that fateful day, the wind was blowing in a northwesterly direction – straight towards Pompeii. 

Detailed eyewitness account
A writer known as “Pliny the Younger” witnessed the eruption from across the Bay of Naples in a small town about 25 kilometers from Mount Vesuvius.  In the only known eyewitness account, this writer and Roman administrator provided a very detailed account of the eruption in a series of letters discovered in the 16th century.  He compared the ash cloud to a (Mediterranean) pine tree and wrote that the cloud had an “unusual size and appearance” and “rose to a great height on a sort of trunk and then split off into branches”.  As it cooled, the tower of debris drifted to earth: first the fine-grained ash, then the lightweight chunks of pumice and other rocks. It was terrifying–“I believed I was perishing with the world,” Pliny wrote, “and the world with me”.  This writer’s uncle known as “Pliny the Elder”, an admiral of the Roman fleet, was actually one of the victims while trying to rescue stranded citizens.

The rediscovering of Pompeii
The site of Pompeii was lost for about 1500 years until its initial discovery in 1599 and then broader discovery almost 150 years later by a group of explorers led by a Spanish engineer in 1748.  When this group rediscovered the site in 1748, they were surprised to find that – underneath a thick layer of dust and debris of between 14 and 17 feet – Pompeii was mostly intact thanks to a lack of air and moisture. The buildings, artifacts and skeletons left behind in the buried city have taught us a great deal about everyday life in the ancient world.  They found that the ashes had acted as a marvelous preservative.  Underneath all that dust, Pompeii was almost exactly as it had been 2,000 years before. Its buildings were intact and everyday objects and household goods littered the streets. Later, archaeologists even uncovered jars of preserved fruit and loaves of bread.  The amphitheater of Pompeii is the oldest stone building of its kind known to mankind, dating back to 80 B.C.  Skeletons were frozen right where they had fallen and plaster was used to fill the voids that once held human bodies.  In fact, this enabled us to see the exact position that a person was when he or she perished in the ash. 

As excavators uncovered human remains, they noticed that the skeletons were surrounded by voids in the compacted ash. By carefully pouring plaster of Paris into the spaces, the final poses, clothing, and faces of the last residents of Pompeii came to life. Photo courtesy: Carlo Hermann/AFP/Getty Images

Today in Pompeii
About three-quarters of Pompeii’s 165 acres have been excavated making it the world’s largest excavation and archaeologist site.  Some 1,150 bodies have been discovered out of about 2,000 thought to have died in the city when it was destroyed.  The vast majority of the city of 20,000 fled at the first signs of the volcanic activity.  Incredibly, as recently as two months ago in June of this year, there were four new skeletons discovered in an ancient shop in Pompeii. The skeletons, which were said to belong to teenagers including an adolescent girl, were scattered on the ground of the shop, together with three gold coins and a necklace pendant. As a result of the Mount Vesuvius eruption of 79 A.D. and other seismic activity over the centuries, Pompeii now stands two kilometers inland, but it was much closer to the sea in ancient Roman times.

Vesuvius is one of the most studied volcanoes in the world because of its long time interval with historic eruptions (about 2000 years) and the fact that it is the first well-documented historic eruption. Mount Vesuvius is the only active volcano on mainland Europe and has not erupted since 1944, but it is still considered to be one of the most dangerous volcanoes in the world; especially, given the fact that over 3 million people live in the immediate area. Today, Pompeii has become a major tourist attraction and it attracts about 2.5 million visitors every year.  

Meteorologist Paul Dorian

Vencore, Inc.