Transcript plinian volcanoes

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
people
o Mt. St. Helens eruption, 57
people died
o Mt. Pinotubo eruption, 800
people died
• The Heights are different
o Mt. Vesuvius is 4,203 ft
o Mt. Pinatubo is 5,840 ft
o Mt. St. Helens is 8,364 ft
Bibliography
http://en.wikipedia.org/
http://www.encyclopedia.com/topic/Mount_Pinatubo.aspx
http://www.volcanolive.com/pinatubo.html
geography.about.com/od/globalproblemsandissues/a/pinatubo.
htm
expo.edu.ph/pinatubo/
http://en.wikipedia.org/wiki/Mount_St._Helens#1980_to_2001_activity
http://ancienthistory.about.com/od/pompeii/p/MtVesuvius.htm
http://geology.com/volcanoes/vesuvius/