93 Eruptions of Vesuvius and Pompeii
Learning Objective
- Describe the events surrounding the Eruption of Mount Vesuvius
Key Points
- The eruption of Mount Vesuvius in 79 CE, during the reign of Emperor Titus, was one of the most catastrophic volcanic eruptions in European history.
- Historians have learned about the eruption from the eyewitness account of Pliny the Younger, a Roman administrator and poet.
- Mount Vesuvius spewed a deadly cloud of volcanic gas, stones, and ash to a height of 21 miles, ejecting molten rock and pulverized pumice at the rate of 1.5 million tons per second, ultimately releasing a hundred thousand times the thermal energy of the Hiroshima bombing.
- Several Roman settlements were obliterated and buried underneath massive pyroclastic surges and ashfall deposits, the most well known of which are Pompeii and Herculaneum.
- The preserved remains of about 1,500 people have been found at Pompeii and Herculaneum, but the overall death toll is still unknown.
Terms
Pliny the Younger
A lawyer, author, and magistrate of Ancient Rome who witnessed the eruption of Mount Vesuvius.
pyroclastic surge
A fluidized mass of turbulent gas and rock fragments, ejected during some volcanic eruptions.
Pompeii
An ancient Roman town-city near modern Naples, in the Campania region of Italy, destroyed during the eruption of Mount Vesuvius.
Overview
Although his administration was marked by a relative absence of major military or political conflicts, Titus faced a number of major disasters during his brief reign. On August 24, 79 CE, barely two months after his accession, Mount Vesuvius erupted, resulting in the almost complete destruction of life and property in the cities and resort communities around the Bay of Naples. The cities of Pompeii and Herculaneum were buried under meters of stone and lava, killing thousands of citizens. Titus appointed two ex-consuls to organize and coordinate the relief effort, while personally donating large amounts of money from the imperial treasury to aid the victims of the volcano. Additionally, he visited Pompeii once after the eruption and again the following year.
The city was lost for nearly 1,700 years before its accidental rediscovery in 1748. Since then, its excavation has provided an extraordinarily detailed insight into the life of a city at the height of the Roman Empire, frozen at the moment it was buried on August 24, 79. The Forum, the baths, many houses, and some out-of-town villas, like the Villa of the Mysteries, remain surprisingly well preserved. Today, it is one of the most popular tourist attractions of Italy and a UNESCO World Heritage Site. On-going excavations reveal new insights into the Roman history and culture.
The Eruption
Reconstructions of the eruption and its effects vary considerably in the details but have the same overall features. The eruption lasted for two days. The morning of the first day, August 24, was perceived as normal by the only eyewitness to leave a surviving document, Pliny the Younger, who at that point was staying at Misenum, on the other side of the Bay of Naples, about 19 miles from the volcano, which may have prevented him from noticing the early signs of the eruption. He was not to have any opportunity, during the next two days, to talk to people who had witnessed the eruption from Pompeii or Herculaneum (indeed he never mentions Pompeii in his letter), so he would not have noticed early, smaller fissures and releases of ash and smoke on the mountain, if such had occurred earlier in the morning.
Around 1:00 p.m., Mount Vesuvius violently exploded, throwing up a high-altitude column from which ash began to fall, blanketing the area. Rescues and escapes occurred during this time. At some time in the night or early the next day, August 25, pyroclastic flows in the close vicinity of the volcano began. Lights seen on the mountain were interpreted as fires. People as far away as Misenum fled for their lives. The flows were rapid-moving, dense, and very hot, knocking down wholly or partly all structures in their path, incinerating or suffocating all population remaining there and altering the landscape, including the coastline. These were accompanied by additional light tremors and a mild tsunami in the Bay of Naples. By evening of the second day the eruption was over, leaving only haze in the atmosphere, through which the sun shone weakly.
Pliny the Younger wrote an account of the eruption:
Broad sheets of flame were lighting up many parts of Vesuvius; their light and brightness were the more vivid for the darkness of the night… it was daylight now elsewhere in the world, but there the darkness was darker and thicker than any night.
Casualties
In Pompeii, the eruption destroyed the city, killing its inhabitants and burying it under tons of ash. Evidence for the destruction originally came from a surviving letter by Pliny the Younger, who saw the eruption from a distance and described the death of his uncle, Pliny the Elder, an admiral of the Roman fleet, who tried to rescue citizens. The site was lost for about 1,500 years until its initial rediscovery in 1599, and broader rediscovery almost 150 years later by Spanish engineer Rocque Joaquin de Alcubierre in 1748. The objects that lay beneath the city have been preserved for centuries because of the lack of air and moisture. These artifacts provide an extraordinarily detailed insight into the life of a city during the Pax Romana. During the excavation, plaster was used to fill in the voids in the ash layers that once held human bodies. This allowed archaeologists to see the exact position the person was in when he or she died.
By 2003, around 1,044 casts made from impressions of bodies in the ash deposits had been recovered in and around Pompeii, with the scattered bones of another 100. The remains of about 332 bodies have been found at Herculaneum (300 in arched vaults discovered in 1980). The percentage these numbers represent of the total dead, or the percentage of the dead to the total number at risk, remain completely unknown.
Thirty-eight percent of the 1,044 were found in the ash fall deposits, the majority inside buildings. These are thought to have been killed mainly by roof collapses, with the smaller number of victims found outside buildings probably killed by falling roof slates, or by larger rocks thrown out by the volcano. This differs from modern experience, since over the last four hundred years only around 4% of victims have been killed by ash falls during explosive eruptions. The remaining 62% of remains found at Pompeii were in the pyroclastic surge deposits, and thus were probably killed by them. It was initially believed that due to the state of the bodies found at Pompeii, and the outline of clothes on the bodies, it was unlikely that high temperatures were a significant cause. But in 2010, studies indicated that during the fourth pyroclastic surge–the first surge to reach Pompeii–temperatures reached 572 °F. Volcanologist Giuseppe Mastrolorenzo, who led the study, noted that “[The temperature was] enough to kill hundreds of people in a fraction of a second.” In reference as to why the bodies were frozen in suspended action, he said, “The contorted postures are not the effects of a long agony, but of the cadaveric spasm, a consequence of heat shock on corpses.”