1. The Eruption of Mt. Vesuvius in AD 79

2. Why Vesuvius?
Mt. Vesuvius lies on a fault, a break in the earth’s crust between the African crustal plate and the European crustal plate
This break results in magma, or molten rock, being forced up to the surface of the earth where one of the plates is being pushed under the other in a process known as subduction
This region is therefore prone to earthquakes and volcanic activity

4. The Collision of the African and European Crustal Plates

5. The Bay of Naples from the Air (notice the size of Mt. Vesuvius)

6. (from what two Latin words does “subduction” derive?)
A Subduction Zone
(from what two Latin words does “subduction” derive?)

7. Mt. Vesuvius
Mt. Vesuvius is a stratovolcano, a volcano built up with layers of magma that create steep sides; this creates the potential for violent eruptions
Mt. Vesuvius had erupted several times in early Roman history, but Romans kept no records of it; it had not had a large eruption since 1800 BC and was building a large magma chamber to breed a catastrophe

8. August 24, AD 79
Earthquakes were the first sign of Vesuvius’ activity in the weeks prior to August 24, AD 79
Prior to that, Vesuvius was simply regarded as a mons (a mountain) that was suitable for growing grapes because of the rich volcanic soil
It was named for Hercules, son of Zeus, who was also known as Ves (in Greek Vesuvious would mean “Son of Zeus”)

10. August 24, AD 79
The eruption began about 1 pm when a giant column of smoke and ash rose in an explosion from the volcano
Soon afterwards, small light stones called pumice and heavier stones fell out of the sky at over 100 miles per hour
The weight of them could cause a headache (ouch!) or collapse roofs
The material ejected is collectively known as tephra

11. The Perfect Storm
As ash blanketed the sky, a wind blowing across the bay kept the ash hovering over Pompeii instead of blowing it out to sea
People began to flee to the shore in hopes of escape – but rescue was not coming
Poisonous gases escaped from the volcanic vent, the most deadly of which were carbon dioxide and hydrogen chloride
Across the Bay of Naples, in Misenum, a young Pliny with is uncle, the Elder Pliny, watched the growing disaster

12. Forms of Tephra: Ash and Pumice

13. Death Comes
During the 19 hour eruption cycle, Vesuvius expelled 1 cubic mile of material
The most deadly material came in the form of a pyroclastic flow – a superheated cloud of gas and ash that came from the collapsing eruption column; it rushed down the side of the mountain at 60 kilometers an hour with a temperature over 600 degrees farenheit
This pyroclastic flow carbonized humans in its path, causing their brains to explode out of their heads

14. A Pyroclastic Flow

15. What Vesuvius Might Have Looked Like on the Day of the Eruption

16. Reconstruction of the Vesuvius Eruption

17. The Eruption of Mt. St. Helens, United States, 1980

18. The Finale
The eruption ended on August 25th with the final collapse of the eruption column blanketing Pompeii and nearby cities with ash
Approximately 3,000 people were killed
Because their remains were carbonized, their body forms were left in the ash for archaeologists to study in the 20th century – the eruption had both destroyed and saved a town