The Eruption The Eruption of of

Mt. VesuviusMt. Vesuvius

August 24, AD 79August 24, AD 79

Why Vesuvius?

Mt. Vesuvius lies Mt. Vesuvius lies on a on a faultfault, a break , a break in the earth’s crust in the earth’s crust between the between the African and African and European crustal European crustal platesplates

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

Subduction ZoneSubduction Zone

This break results This break results in in magmamagma, , or or molten rock, being molten rock, being forced up to the forced up to the surface of the surface of the earth where one of earth where one of the plates is being the plates is being pushed under the pushed under the other in a process other in a process known as known as subductionsubduction

Mt. VesuviusMt. Vesuvius

Mt. Vesuvius is a Mt. Vesuvius is a stratovolcanostratovolcano, a , a volcano built up volcano built up with layers of with layers of magma that create magma that create steep sides steep sides

This structure This structure creates the creates the potential for potential for violent eruptionsviolent eruptions

Mt. Vesuvius

Mt. Vesuvius had Mt. Vesuvius had erupted several times erupted several times in early Roman in early Roman history, but Romans history, but Romans kept no records of it; kept no records of it;

Vesuvius had not Vesuvius had not erupted since 1800 erupted since 1800 BC and was building BC and was building a large magma a large magma chamberchamber

Mt. VesuviusMt. Vesuvius In 79 AD Vesuvius was In 79 AD Vesuvius was

simply regarded as a simply regarded as a monsmons that was suitable that was suitable for grape cultivation for grape cultivation because of the rich because of the rich volcanic soilvolcanic soil

Mt. Vesuvius was Mt. Vesuvius was named for Hercules, son named for Hercules, son of Zeus (Ves: in Greek of Zeus (Ves: in Greek Vesuvious would mean Vesuvious would mean “Son of Zeus”) “Son of Zeus”)

August 24, 79 AD August 24, 79 AD

Earthquakes were the first sign of Earthquakes were the first sign of Vesuvius’ activity leading up to August Vesuvius’ activity leading up to August 24, 79 AD 24, 79 AD

The eruption began about 1 pm with a The eruption began about 1 pm with a giant column of smoke, ash exploding giant column of smoke, ash exploding from the volcano, material (from the volcano, material (tephra) tephra) ejected from the columnejected from the column

August 24, AD 79August 24, AD 79

Small light stones called Small light stones called pumicepumice and and heavier stones fell out of the sky at over heavier stones fell out of the sky at over 100 miles per hour100 miles per hour

Vesuvius expelled 1 cubic mile of Vesuvius expelled 1 cubic mile of material in 19 hoursmaterial in 19 hours

The weight of the ash and pumice The weight of the ash and pumice collapsed roofscollapsed roofs

Forms of Tephra: Ash and Forms of Tephra: Ash and PumicePumice

What Vesuvius Might Have Looked Like on the What Vesuvius Might Have Looked Like on the Day of the EruptionDay of the Eruption

The Perfect StormThe Perfect Storm

As ash blanketed As ash blanketed the sky, a wind the sky, a wind blowing across the blowing across the bay kept it hovering bay kept it hovering over Pompeii over Pompeii instead of blowing instead of blowing it out to seait out to sea

People began to flee People began to flee to the shore in to the shore in hopes of escape – hopes of escape – but rescue was not but rescue was not comingcoming

The Perfect StormThe Perfect StormPoisonous gases

vented from the volcano, the most deadly of which were carbon dioxide and hydrogen chloride

Across the Bay of Naples, in Misenum, a young Pliny with his uncle, Pliny the Elder, watched the growing disaster

Death ComesDeath Comes

The most deadly material came in the form The most deadly material came in the form of a of a pyroclastic flow pyroclastic flow – a superheated cloud – a superheated cloud of gas and ash formed from the collapsing of gas and ash formed from the collapsing column – moving at 60 kph with a column – moving at 60 kph with a temperature over 600B Ftemperature over 600B F

Pyroclastic FlowPyroclastic Flow

Reconstruction of the Vesuvius Eruption

The Victims of VesuviusThe Victims of VesuviusThe eruption ended The eruption ended

on August 25on August 25thth with with the final collapse of the final collapse of the eruption the eruption column blanketing column blanketing Pompeii and nearby Pompeii and nearby cities with ashcities with ash

Approximately Approximately 3,000 people were 3,000 people were killedkilled

The Victims of VesuviusThe Victims of Vesuvius

Because their Because their remains were remains were carbonized, their carbonized, their body forms were body forms were left in the ash for left in the ash for archaeologists to archaeologists to study in the 20study in the 20thth century – the century – the eruption had eruption had both destroyed both destroyed andand saved a town saved a town

The Eruption of Mt. St. Helens, 1980The Eruption of Mt. St. Helens, 1980