Vesuvius from a plane Vesuvius, one the world's most famous volcano, looms above the Bay of Naples. It exploded with huge force on August 24, A.D. 79 and buried the cities of Pompeii and Heracuelum and killed many of their residents.
Vesuvius (10 miles from Naples) is 4,203 feet (1,281 meters) high. It is now relatively quiet but still very active. The bottom of the crater is about 800 feet below the crater rim. Several fumaroles innocuously release fumes. Vesuvius actually lies inside the exploded remnants of an older volcano. A ridge from the much large volcano lies on the north edge.
The chamber where Vesuvius’s magma is stored is seven miles below the earth's surface. The collision between the African plate and the European plate in southern Italy produces molten rock, rich in volatile gases. Under pressure these gases stay dissolved. But when the magma rises to the surface, the gases expand and when they are released they tend to produce explosive eruptions.
Vesuvius from a satellite Some scientists regard Vesuvius as the world's most dangerous volcano. An estimated 1 million people live within the "death zone" five miles of the crater and three million live within an eight-mile radius of the crater. Should the volcano repeat its Pompeii performance ashfall, pyroclastic flows, and mud slides would probably destroy 500,000 homes and kill 200,000 people if no warnings were given and no preparations were made. A huge pyroclastic flow like the one that occurred in 1780 B.C. could wipe out all of Naples.
A large eruption in 1631, when there was only a 24 hour warning that something was amiss, killed 4,000 people. Streams of lava were produced by frequent eruptions in the 18th, 19th and 20th centuries but few people were hurt. The last major eruption occurred during World War II in 1944, when there were small ash showers and a small lava flow. Clouds of ash blew towards U.S. bombers as they headed toward German targets. About 45 people were killed and 88 Allied aircraft based nearby were damaged. Some serious damage occurred in some places but the eruptions was nothing like the one in A.D. 79. Since 1944 the volcano has been mostly quiet. Some say this is bad news: a sign that pressure is building up inside and it could blow violently when next time it erupts.
The area around Vesuvius is the only real volcanically active region of the European mainland. Nearby on the island of Ischia is a volcano that erupted in 1302 and opposite the Bay of Naples from Vesuvius are the Phlegraean Fields which are made up of 20 craters, including one, Monte Nuovo, which was formed by an eruption in 1538. About 36,000 years ago an eruption occurred here that dwarfed both Krakatau and Mount St. Helens and covered the area with a layer of ash 160 feet thick. In the 1980s the region started to kick up again but all is quiet now.
Eruptions of Vesuvius
Vesuvius lets loose with a major eruption about once every 2000 years. The last one was the famous one that destroyed Pompeii in B.C. 79. The one before that was in 1780 B.C. Before that there were major ones about 8,000 years ago, 11,400 years ago, 15,000 years ago, 17,000 years ago, 22,500 years ago and 25,000 years ago.
Vesuvius is plugged by a huge cork of solid rock, which according to some estimates is 10 kilometers thick. It takes a huge amount of energy and pressure for the magma chamber below the rock to blow a hole to the surface. When Vesuvius erupts it typically releases a massive column of hot ash and stones, mostly light. air-hole-filled pumice and harder, more rock-like lapilli. Liquid rock is propelled into the air at supersonic speeds, producing a sonic boom. The cloud of material produced in A.D. 79 that Pliny the Younger wrote was shaped like an umbrella pine tree.
The way the eruption unfolds and the damage occurs depends on where the crater on the volcano is (which determines where the pyroclastic flows might go) and wind directions (which determines where the ash cloud will go). Eruption occurring in ancient Monte Somma crater have funneled pyroclastic flows in the direction of Naples. Wind in 1780 B.C. carried the fallout mainly to the east while winds in B.C. 97 carried debris from that eruption to the south towards Pompeii.
The height of the Vesuvius changes from eruption to eruption. It looks now like the top half of the mountain is missing, which is in partly true. The mountain was several hundred feet higher in A.D. 79. It is now 4,203 feet high, 140 feet or so shorter than it was during its last major eruption in 1906. Vesuvius's major eruptions occur at the end of a cycle that begins with a 7 year quiescent period which is followed by 20 to 30 years of minor activity before the mountain finally blows.
Pyroclastic Surges and Mudlfows from Vesuvius
During Vesuvius eruptions a column of ash, gas and heated rock collapses on itself, creating burning hot clouds in a pyroclastic surges that shoot out sideways and flow down the slopes initially at great speed, destroying everything in their path. Many volcanos have produced pryoclastic flows but the ones produced by Vesuvius cover many kilometers, making Vesuvius in the eyes of some experts perhaps the world’s most dangerous volcano.
Stephen Hall wrote in National Geographic, “A pyroclastic surge is baked in a subterranean chamber to temperatures of up to 1650 degrees F. The initial surge of the eruption, especially in the zones closest to Vesuvius is instantly lethal. Hot, choking, wind, advancing at about 240 miles an hour, reach temperatures of at least 900 degrees F, and retain enough heat to bring water to a boil ten miles from the event.”
Giuseppe Mastrolorenzo, a volcanologist at the Osservatorio Vesuviano in Naples, told National Geographic, “Below 200 degrees Fahrenheit, you can survive for several seconds, perhaps if the wave passes quickly...But even if you survive the temperature , you will suffocate on the fine powder in the air.”
“When vast amounts of solid ash and debris mixes with steam fed by underground aquifers,” Hall wrote, “a violent microclimate of pitched thunderstorms and torrential rains occurs, producing great mudflows. Ash falling into rivers creates more mudflows, known as lahars, that fill river valleys long after the eruption is over.” Mastrolornzo said, “There are more victims from the mudlfows than from the eruption itself. These mud flows travel with a force that moves houses hundreds of meters,”
Avellino Eruption of Vesuvius in 1780 B.C.
Vesuvius1872 In 1780 B.C. Vesuvius exploded with more powerful blast than it did in A.D. 79. A pyroclastic surge and flow engulfed an area to the north of the volcano about 30 kilometers north to south and 30 kilometers east to east and destroyed almost everything in its path. This is a huge area, covering all of modern-day Naples and its suburbs and much of the countryside surrounding it too. [Source: Stephen Hall, National Geographic, September 2007]
Mastrolorenza and Peir Paolo Petrone, an anthropologist at the University of Naples, are two figures who have been at the forefront of trying to figure what happened during the 1780 B.C. eruption geologically and anthropologically. They have done this primarily by measuring ash depths in different places and studying footprints of victims as they fled the eruption. The eruption is sometimes called the Avellino eruption because volcanic material was found at the town of Avelliono about 40 kilometers to east.
Mastrolorenzo, Petrone and American volcanologist Michael Sheriden sparked interest in the eruption in the spring of 2006 with a paper about it in the Proceeding of the National Academy of Sciences (PNAS) in which they said the Avellion event “caused a social-demographic collapse and the abandonment of the entire area for centuries.”
Vesuvius in 1822 The initial blast hurled material---cinders, heated rock and ash---at a rate of 100,000 tons a second. A column reached about 35 kilometers into the stratosphere---roughly three times the altitude of cruising commercial airliners. The column of ash may have hung in the air for as long as 12 hours. Pumice and lapilli collected into piles as high as three meters near the volcano. This eruption and what occurred afterwards also offers a scary warming what is store for the modern Naples metropolitan area, and its three million people, sometime in the not too distant future. If an Avellino eruption occurred without warning today everyone in Naples would die.
Describing what the blast must have been like for villagers from 1780 B.C. whose bones were found in 1995, Stephen Hall wrote in National Geographic, “When the first thunderous boom echoed across the plain of Campania, quickly followed by a blistering hail of volcanic rock, the men and the woman had abandoned their village and made a run for it to the east.. A violent downpour of rubbly pumice mixed with incandescent rocks capable of crushing skulls and scalding skin obscure their escape....Thousands of other people were at the same moment running for their lives, marking the soft ash and wet volcanic mud with footprints...The people whose footprints led to the north or northwest chose a path that probably saved their lives; those who set out to the east...unwittingly chose a bath that led them to certain death. They headed by ill luck, smack into the middle of a fallout zone that would swiftly bury them under three feet of pumice.” Victims either died from trauma wounds caused by being struck on the head by large volcanic rocks of by being slowly asphyxiated.
Mastrolornzo told National Geographic, “The entire countryside surrounding Vesuvius was covered by foot upon foot of the powder produced by the pyrcoclastic flow: “645 feet deep at a distance of three miles from the crater and about 10 inches thick at a distance of 15 miles. Eight inches of ash is enough to cause modern roofs to collapse.”
Eruption of Vesuvius in A.D. 79
At about 1:00pm on August 24, A.D. 79 Vesuvius exploded like a nuclear weapon. After about a half an hour volcanic debris started to cover Pompeii. For 11 hours the volcano thrust a column of pumice, ash and fumes 20½ miles into the stratosphere at a rate of 1.5 million tons per second, turning day into night and releasing more thermal energy than 100,000 Hiroshima atomic bombs. Warning signs before the eruption included an earthquake a few weeks before and wells mysteriously going dry. There was no lava, the eruption was too violent for that.
As the column of ash and cinders cooled it began to spread horizontally and drift with the wind. As it cooled further solid particles began raining down. Pompeii and the ancient city of Stabiae were buried under the volcanic debris while Heracuelum succumbed to fiery avalanches of gas and volcanic debris. The event is sometimes called the pliny eruption because it was described by great Roman scholar Pliny the Elder and his nephew Pliny the Younger.
There were 15 earthquakes before Mt. Vesuvius erupted and covered Pompeii.
Vesuvius and Pompeii
Effect of the Eruption of Vesuvius in A.D. 79 on Pompeii
Pompeii's fate of being downwind from Vesuvius on that day had more to do than anything else with it being buried by ash. Ash and pumice fell on Pompeii at a rate of six inches an hour. This in itself wasn't enough to kill anyone at first, but mixed in were bowling-ball-size volcanic bombs that were. After four hours roofs began to collapse from the weight of the ash and after 17 hours over 9 feet of ash had fallen.
An estimated 80 percent of Pompeii's resident probably survived by fleeing early. Those that stayed were probably able to survive the ashfall of the first day, if their roofs didn't collapse, by staying indoors and breathing through rags. But on second day, just as the ash was starting to let up and people began venturing outdoors, pyroclastic flows of superheated gas and ash surged through the city. These flows reached Pompeii on August 25. The first at 5:30am stopped just outside Pompeii's walls. The second one, an hour later, entered the city and probably asphyxiated most of its residents. The third and most devastating surge is the one that caused Pliny to flee Misenum. This one, which came three hours after the first, buried Pompeii and entombed its victims.
After that there were more pyroclastic surges as well as mud flows, but by that time everyone that was going to die was already dead, Hall wrote: “The pattern of its deposits, the swirl of its volcanic signature in layers thick and thin, has allowed volcanologists to conclude that Vesuvius unleashed at least six cycles of pyroclastic surge and flow in that single eruption’six bursts of searing winds followed by six rampaging rivers of mud---that destroyed everything within about nine miles of the volcano. The immediate cataclysm probably lasted less than 24 hours, but it turned an idyllic landscape into a monochromatic desert, uninhabitable for 300 years,”
from the Discovery Channel TV show Last Day of Pompeii
Death at Pompeii from Eruption of Vesuvius
About 2,000 people died in Pompeii. Many it is believed initially fled but returned to collect their money and belongings. Not many died during the initial ash fall. Many died after being trapped in ash for hours. Most of the dead perhaps were killed in a 30 second thermal blast and pyroclastic surge. Many died pressing pillows ro their faces in a vain attempt to keep from inhaling gas. Many also died clinging to valued possessions or objects that might bring them good luck.
Describing a possible scenario for the death for four people on the second day of the eruption, Doug Stewart wrote in Smithsonian magazine, “under a lurid and sulfurous sky, a family of four struggles down an alley filled with pumice stones, desperately trying to escape the beleaguered city of Pompeii. Leading the way is a middle-aged man carrying gold jewelry, a sack of coins and the keys to his house. Racing to keep up are his two small daughters, the younger one with her hair in braids. Close behind their mother, scrambling frantically through the rubble with her skirts hiked up. She clutches an amber statuette of a curly-haired boy, perhaps Cupid, and the family silver, including a medallion of Fortuna, the goddess of luck.”
“But neither amulets nor deities can protect them. Like thousands of others this morning, the four are overtaken and killed by an incandescent cloud of scorching gases and ash from Mount Vesuvius. In the instant before he dies, the man strains to lift himself from the ground with one elbow. With his free hands, he pulls a corner of his cloak over his face, as though the thin cloth will save him.”
Plaster Casts of the Dead at Pompeii
ash deposits from AD 79 eruption The most memorable and shocking reminders of what happened at Pompeii are the plaster casts that have been made of the victims whose bodies left cavities in the hardened volcanic debris. The cavities---which served as molds for the plaster casts---were created when volcanic ash mixed with rainwater and hardened around the victims, whose bodies rotted away over the years. Grim images of the dead have been made by pouring plaster into cavities. The technique was first used in 1863 by Italian archaeologist Giuseppe Fiorelli who noticed four cavities in the hardened ash and filled them with plaster, revealing lifelike castes.
The cavities of around 2,000 people have been found in Pompeii. Among them are ones made by a pregnant women on her back, her husband covering her mouth with his own in a last kiss or mouth to mouth resuscitation. Casts have been made of a baby, curled up tightly, on its back, another baby sprawled on its back, a man climbing some stairs, a man crouching holding his face, and a woman hugging and protecting her baby. The cast of a child with upward-thrusting arms is so detailed you can see that his eyes were closed and his mouth was open. He was found with his parents and a younger sibling in the House of the Golden Bracelet, under a staircase, which collapsed and killed them. There are also casts of animals, including a chained dog.
Describing the deaths of what were probably slaves Stewart wrote in Smithsonian magazine, “During the night of the 24th, the worsening rain of ash and stones blocked doors and windows on the ground floor and poured through atrium skylights at the House of Meander, one of the city’s grandest homes. In the darkness a group of ten people with a single lantern...tried fanatically to climb from the pumice-filled entrance hall to the second floor. . In a nearby hall facing a courtyard, three more struggled to dig an escape route with a pick ax and a hoe. All died.” One reason they are thought to have been slaves is that were found with few possessions other than a couple coins and a few glass beads. Those that died with valuable object were reasoned to be wealthy citizens.
Effect of the Eruption of Vesuvius in A.D. 79 on Herculaneum
cast of a baby Most of the dead at Herculaneaum perished instantaneously when a pyroclastic flow surged through the city. The vast majority of Herculaneum’s roughly 5,000 inhabitants probably escaped before that happened as only a few dozen people have been found in the city itself.
Describing what happened to them, Doug Stewart wrote in Smithsonian magazine, “Shortly after noon on August 24, the sky over Herculaneum darkened ominously, The wind, however, pushed Vesuvius ash well to the southeast...Not long after midnight, a glowing cloud of superheated gas, ash and debris roared down the mountain’s western flank towards the sea....Large numbers of Herculaneum’s residents had fled towards the sea in hopes of escaping by boat.”
Geologist Phil Janney told Smithsonian magazine: “Pyroclastic surges move quite rapidly , between 50 and 100 miles per hour, You can’t outrun then. You don’t even get much warning.” A large number of people appeared to have been trapped in boats, where they were burned alive by a pyroclastic surge that was so hot it melted coins into solid blocks of bronze and silver.”
Death at Herculaneum from Eruption of Vesuvius
cast of a dog Few human remains had been found in Herculaneum. In the 1980s archaeologists discovered the remains of nearly 300 dead, including 150 bodies that were discovered in 1982 in a group of warehouses near the seafront, where they apparently had fled. Some of the skulls have clenched teeth, others have their mouths wide open, testimony that they died a sudden, painful death. The find was also valuable archaeologically. Since the Romans cremated their dead there are very few Roman skeletons.
One chamber contained the remains of 12 people huddled together, a few of them embracing each other. Cradled in the arms of one adult was an infant. The head of another was buried facedown, as if sobbing, into a pillow. In a nearby chamber are the tangled remains of 40 individuals, and one horse, that looked to be in panic and chaos when their final moments arrived. An in yet another chamber the bodies where organized into neat rows as if they were rowing a huge ghost ship.
The remains of a pregnant woman were found along with a tiny skeleton of her seventh-month fetus. Another woman later called the Ring Lady was found with two large jeweled rings and two exquisite gold bracelets shaped like serpents with heads at each end. A third woman, with buck teeth, was judged to be a prostitute by the structure of her pelvic bones. The analysis a 45 year old man showed him to be undernourished, overworked and in continual pain as a result of his rotting teeth and fused discs in his spine.
In 2001, Petrone and Mastrolorenzo published a paper in the journal Nature providing evidence that hundreds of fugitives who gathered in 12 seafront fornci , or boathouses, facing the beach of Herculaneum died instantly from a pyroclastic surge that reached temperatures of 932 degrees F, vaporizing clothing and flesh within seconds. The victims were huddled together in groups of 5,10 and 12. From the position of the bones the scientists determined they died instantly. Small black and blue marks left on skulls were caused when brain tissue boiled and exploded and splattered on the skulls. Moisture from vaporized flesh and blood combined to create a protective, plasterlike material that preserved bones. Much of Herculaneum still lies under 20 meters of hard rock and it is difficult to determine the exact number of dead there.
Pliny the Elder and the Eruption of Vesuvius
While most people headed as quickly as they could away from Pompeii, the very curious Roman historian and naturalist Pliny the Elder headed straight for it. At the time of the eruption Pliny and his nephew, Pliny the Younger, were across the Bay of Naples, 15 miles from Vesuvius and 20 miles away from Pompeii. The elder Pliny considered the eruption a novelty and, taking a Roman fleet with him, sailed towards Pompeii. The nephew initially stayed behind and wrote an account of what happened, apparently pieced together from his own observations and the accounts of survivors.
Pliny the Younger wrote that Pliny the Elder "had been out in the sun, and taken a cold bath" and "my mother drew his attention to a cloud of unusual size and appearance...It was not clear from which mountain the cloud was rising. Later we knew it was Vesuvius...My uncle's scholarly acumen saw at once it was important enough for a closer inspection and he ordered a boat to be made ready."
"He was entirely fearless...he hurried to the place everyone else was hastily leaving...Ashes were already falling, hotter and thicker as the ships drew near." His boat was bombarded with fiery ashfall and blocked with floating rafts of pumice but eventually he made it to Stabiae which was about the same distance from Pompeii as Pompeii was from Vesuvius.
To calm his friends Pliny told them "the broad sheets of fire and leaping flames" were "nothing but the bonfires left by peasants." Later, while his companions debated whether to stay in their house or flee, Pliny slept soundly through the first night of the eruption. When the houses starting shaking violently, they put pillows on their heads to protect themselves from falling rocks.”
Pliny the Elder died in the eruption of Vesuvius. He advised calm when the volcano began erupting and stayed in Pompeii even though he had enough warning to escape. He went outside the day after the initial eruption, on August 25, with a pillow tied to his head. Some think that Pliny the Elder died choked by ash after landing in the beach near Pompeii.
Pliny the Younger wrote that August 25, was "blacker and denser than any ordinary night." Violent waves made escape by sea impossible. Pliny grew tired and repeatedly asked for cold water. Then suddenly the "flames and smell of sulphur" drove his companions to flight. The elder Pliny collapsed, perhaps from a heart attack or from breathing in toxic fumes, and two days later his body was found on a beach at Stabiae "entire an uninjured...its postured that of sleeping, rather than a dead man."
Pliny the Younger and the Eruption of Vesuvius
Garden of the Fugitives Meanwhile, Pliny the Younger, who was a safe enough distance away in Minsenum, was interrupted from his studies by a "fearful black cloud” that “was rent by forked and quivering bursts of flame." The cloud moved across the bay "and parted to reveal great tongues of fire like flashes of lightning magnified in size...We also saw the sea sucked away and apparently forced back by the earthquake.” He described the initial cloud as being of “unusual size and appearance.” He said it reminded him of an umbrella pine tree “for it rose to a great height on a sort of trunk and then split off into branches.”
Pliny the Younger fled along with most of the other terrified residents of Misenum. As the cloud descended," many besought the aid of the gods, but still more imagined there were no gods left, and that the universe was plunged into darkness for evermore."
"You could hear the shrieks of women and wailing of infants, and the shouting of men: some were calling for their parents, others their children and wives...There were people, too, who added to the real perils by inventing factious dangers: some reported that a part of Misenum had collapsed or another part was on fire."
"The flames remained a distance off; then darkness came on once more and the ashes began to fall again, this time in heavy showers. We rose from time to time and shook them off, otherwise we should have been buried and crushed beneath the weight.” When the cloud eventually lifted “everything changed, buried deep in ashes like snowdrifts."
Image Sources: Wikimedia Commons, The Louvre, The British Museum
Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Yomiuri Shimbun, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications. Most of the information about Greco-Roman science, geography, medicine, time, sculpture and drama was taken from "The Discoverers" [∞] and "The Creators" [μ]" by Daniel Boorstin. Most of the information about Greek everyday life was taken from a book entitled "Greek and Roman Life" by Ian Jenkins from the British Museum [||].
© 2008 Jeffrey Hays
Last updated January 2012