Vesuvius

And other Plinian Eruptions

 Plinian Eruptions

 

•Largest kind of eruption •Also known as “Vesuvian eruptions” •Ash has been known to been pushed about 28 miles into the sky •Named after Pliny the Younger   

 How to identify a Plinian Eruption

•Plinian eruptions send columns of ash and gas high into the stratosphere •The eruption can last from days to months •Ejects large amount of pumice •Continuous powerful gas blast eruptions 

Mount Vesuvius's Plinian Eruptions

 

Background

• Located in Italy on the coast of the Bay of Naples •  It is the most densely populated volcanic region in the world

 •  It was formed by the collision of the African and Eurasian

Tectonic Plates •  It has had several eruptions that vary greatly in severity

  

Leading Up to the Eruption of 79 AD

• A powerful earthquake happened 17 years before AD 79 • Some of the damage from the earthquake had not been

rebuilt when the eruption came  • Additionally, a small earthquake occured in 64 AD

 •  On August 20, AD 79, small earthquakes started occuring

 • The Romans grew used to the mild tremors near Vesuvius 

Eruption of 79 AD

• Produced white ash •  Had two phases, the plinian eruption, and

the pyroclastic flow •  Erupted on August 24th and 25th • People did not react immediately because

they were used to mild tremors   

Aftermath

• 10,000-25,000 people died• 38% of the victims were found in the

ash fall deposits• 62% if the victims were killed by

pyroclastic surge deposits• Erupted about 1 cubic mile of rock

and ash• Lasted 19 hours

Eruptions after 79 AD

• Had severe eruptions in 512• Other eruptions were noted in 787,

968, 991, 999, 1007, 1036• Had an extremely destructive eruption

in 1631• Almost continuous eruptions

continued after that until 1944

Mount Pinatubo

Background Information

• Located in the Philippines o The Tri-Cabusilan Mountain

range o The island of Luzon

• 5,840 ft (1,780 m) high• Formed when Philippine Mobile

Belt slid over Eurasian plate• 500,000 people are still living

within 40km• It has been over 450 years

since the previous one

Leading Up to the Eruption• 7.7 Earthquake occurred

100 km northeast on July 16,1990

• A succession of earthquakes were felt on March 15, 1991

• Experts decided that volcanic activity was occurring

•  60,000 people were evacuated

• Small phreatic eruptions started on April 2 

 

The Eruption

• Magma first erupted on June 3rd

• The first explosive eruption was June 7th o This forced ash 7km into the

air• A second eruption on June

12th had ash column 19km high

• Later that day an eruption had an ash column 24km high

The Climatic Eruption

• On June 14th the largest eruption hit o The ash column went 34km

into the air• Typhoon Yunya hit the Philippines

the same day• Rain caused many lahars, or

mudslides that destroyed surrounding forests

• Throughout all eruptions, pyroclastic flows reached as far as 16 km away

Aftermath

• All in all, Mt. Pinatubo ejected 10 cubic km of material o This is 10 times larger than

Mt. St. Helens• 800 people died

o would have been more without evacuation

• VEI rating of 6; Mt. St. Helens was rated 5 o (Volcanic Explosivity Index)

• nd largest eruption of the 20th century

Mt. St. Helens

 

Mount St. Helens

-8,365 feet (2550 m)-Location: Skamania County, Washington, USA-Mount St. Helens most famous eruption was on May 18, 1980 at 8:32 am, which was the deadliest and most economically destructive volcanic event in the history of the U.S.

1980 Eruption

-Mount St. Helens experienced a 4.2 magnitude earthquake on the 20th of March, and steam started venting seven days later.-The mountain stated to bulge about four weeks later and on May 19th, a 5.1 magnitude earthquake started a massive collapse of the north side of the mountain.-It then released the largest amount of debris ever recorded.-Over 1.5 million metric tons of sulfur dioxide was released into the air.-Volcanic mudflows destroyed bridges and lumber camps, and a total of 3,900,000 cubic yards of material was transported 17 miles south.-Ash traveled up to 16 miles above sea level; the ash reaching Idaho by noon and even collected on cars and roof as far as Edmonton in Alberta, Canada.

Aftermath

-fifty seven people were killed-two hundred fifty homes, forty seven bridges, fifteen miles of railways and one hundred eighty five miles of highway were destroyed. -The eruption caused a massive debris avalanche, reducing the elevation of the mountain's summit from 9,677 feet to 8,365 feet and replacing it with a one mile wide horseshoe-shaped crater.

Similarities

• All three volcanoes have erupted in the last century

• Evacuation plans o Mt. Pinatubo and Mt. St.

Helens evacuated o This saved many lives

• Citizens of Pompeii were ignorant o Many died who could

have been saved•  All are still active today • Another large eruption is

bound to occur • Hopefully, the world will be

ready and evacuated Mt. St. Helens

Differences

• Different amounts of people were killed in all three eruptions:o Vesuvius killed 10,000-25000

peopleo Mt. St. Helens eruption, 57

people died o Mt. Pinotubo eruption, 800

people died• The Heights are different

o Mt. Vesuvius is 4,203 fto Mt. Pinatubo is 5,840 fto Mt. St. Helens is 8,364 ft

Bibliography

http://en.wikipedia.org/http://www.encyclopedia.com/topic/Mount_Pinatubo.aspxhttp://www.volcanolive.com/pinatubo.htmlgeography.about.com/od/globalproblemsandissues/a/pinatubo.htmexpo.edu.ph/pinatubo/ http://en.wikipedia.org/wiki/Mount_St._Helens#1980_to_2001_activity

http://ancienthistory.about.com/od/pompeii/p/MtVesuvius.htmhttp://geology.com/volcanoes/vesuvius/