PompeiiPompeiiThe Last DayThe Last Day

The inhabitants of Pompeii did not The inhabitants of Pompeii did not know Vesuvius was a volcano. It know Vesuvius was a volcano. It hadn’t erupted in 1800 years. In hadn’t erupted in 1800 years. In fact, there was no word in Latin for fact, there was no word in Latin for volcano. Volcanoes were volcano. Volcanoes were sometimes called “Fire Mountains.”sometimes called “Fire Mountains.”

The longer a volcano remains The longer a volcano remains dormant, or “sleeps,” the more deadly dormant, or “sleeps,” the more deadly the eruption. There were signs that the eruption. There were signs that Vesuvius was beginning to stir. These Vesuvius was beginning to stir. These signs included earthquakes, ground signs included earthquakes, ground rising up, and underground springs rising up, and underground springs drying up. Unfortunately, the people drying up. Unfortunately, the people of Pompeii and Herculaneum didn’t of Pompeii and Herculaneum didn’t know how to read these signs or know how to read these signs or understand what they meant.understand what they meant.

A reservoir of magma 3 Km wide had A reservoir of magma 3 Km wide had formed below Vesuvius, trapped formed below Vesuvius, trapped inside by a plug of old magma. A inside by a plug of old magma. A chemical reaction involving water and chemical reaction involving water and gases finally shattered the lava plug gases finally shattered the lava plug and Vesuvius roared back to life.and Vesuvius roared back to life.

The eruption of AD 79 was very unusual, without The eruption of AD 79 was very unusual, without lava or other characteristics normally associated lava or other characteristics normally associated with volcanoes. It was a Plinian eruption, the with volcanoes. It was a Plinian eruption, the most dangerous and feared kind of all. These most dangerous and feared kind of all. These eruptions are named after “Pliny the Younger” eruptions are named after “Pliny the Younger” who described the AD 79 eruption in a letter. This who described the AD 79 eruption in a letter. This type of eruption involve superheated gas, magma type of eruption involve superheated gas, magma and ash that form a giant towering column that and ash that form a giant towering column that builds up into the sky. The magma cools and falls builds up into the sky. The magma cools and falls to the Earth as pumice. Vesuvius erupts in this to the Earth as pumice. Vesuvius erupts in this way approximately every 2000 years.way approximately every 2000 years.

Mixed with the pumice stones were Mixed with the pumice stones were lithics lithics (volcanic bombs), dense rocks torn (volcanic bombs), dense rocks torn from the inside of the volcano and from the inside of the volcano and carried up into the atmosphere only to carried up into the atmosphere only to fall back to the Earth at speeds reaching fall back to the Earth at speeds reaching 186kph.186kph.

The eruption took just under 24 The eruption took just under 24 hours from start to end.hours from start to end.

Had the eruption taken place on any Had the eruption taken place on any other day, the people of Pompeii might other day, the people of Pompeii might have stood a better chance of escape. have stood a better chance of escape. Usually, the wind blew in a southwesterly Usually, the wind blew in a southwesterly direction, which would have blown the direction, which would have blown the column out over the Bay of Naples. But, column out over the Bay of Naples. But, on that fateful day, the wind was blowing on that fateful day, the wind was blowing in a northwesterly direction straight over in a northwesterly direction straight over Pompeii.Pompeii.

Vesuvius ejected more than 4 cubic Km of Vesuvius ejected more than 4 cubic Km of material over Campania (southern Italy) that material over Campania (southern Italy) that day. Ash fall was traced as far away as day. Ash fall was traced as far away as Africa.Africa.

The seaside resort of Herculaneum The seaside resort of Herculaneum was buried under 25 meters of was buried under 25 meters of pyroclastic material, extending the pyroclastic material, extending the coast line by 450 meters.coast line by 450 meters.

Vesuvius emitted enough ash to Vesuvius emitted enough ash to fill a cube 1.5 miles on each side.fill a cube 1.5 miles on each side.

Pompeii was first uncovered in1594, Pompeii was first uncovered in1594, although archeological excavations only although archeological excavations only began in 1748 and have continued since began in 1748 and have continued since then. A massive area has now been then. A massive area has now been excavated; however, even today, more than excavated; however, even today, more than a quarter of Pompeii still awaits excavation. a quarter of Pompeii still awaits excavation.