35
Volcanoes Lesson #10 Volcanoes Objective: Describe the main features and characteristics of volcanoes. Be explain to name and explain the three separate types.
VolcanoesLesson #10 Volcanoes
Objective: Describe the main features and characteristics of volcanoes. Be
explain to name and explain the three separate types.
! Volcano: An opening in the earth's crust through which molten magma and gases erupt.
Copyright © 2010 Ryan P. Murphy
! Ring of Fire: A zone of frequent earthquakes and volcanic eruptions that encircles the basin of the Pacific Ocean.
Copyright © 2010 Ryan P. Murphy
Where do volcanoes occur?
! Occur at convergent boundaries ! In subduction zones
4
! Composite or Stratovolcano.
Copyright © 2010 Ryan P. Murphy
! Mount Saint Helens
Yellowstone National Park
Largest volcano
on the planet
Caldera
! Caldera Volcano: Large crater caused by the violent explosion of a volcano that collapses into a depression.
! Supervolcano: A volcano capable of producing a super volcanic eruption with ejecta greater than 1000 cubic kilometers.
! This is the range of serious destruction if the Yellowstone Supervolcano were to erupt.
Copyright © 2010 Ryan P. Murphy
! Explosions happen about “every 600,000 years at Yellowstone,"
! "And it's been about 640,000 years since the last super explosive eruption there."
Copyright © 2010 Ryan P. Murphy
! The Hot Spot under the continent has erupted periodically throughout history.
Copyright © 2010 Ryan P. Murphy
N. American
Plate
OlderToday
! The rest of the United States would be buried in 1 meter of Ash.
Copyright © 2010 Ryan P. Murphy
! The rest of the United States would be buried in 1 meter of Ash. ! The global climate would shift for many years as dust
clouds would block out the sun. ! Agriculture would become difficult.
Copyright © 2010 Ryan P. Murphy
! Which Island is the oldest? Youngest
Copyright © 2010 Ryan P. Murphy
A
B
CD Only Island with active volcanoes
Older
ErosionIslands get smaller
New Earth/
Growth
! Hawaii is caused by a hot spot: A location above an upwelling of magma from the mantle.
Copyright © 2010 Ryan P. Murphy
! Why do volcanoes erupt? ! When rock from the mantle melts, it moves
to the surface through the crust, and releases pent-up gases which can erupt.
! Activity! Volcanic Explosion. ! A volcano is a lot like a bottle of soda exploding. ! Like soda, molten earth contains gases. ! These gases create a frothy cloudy explosion. ! Note the air spaces in the volcanic rock Pumice. ! Make tube to drop entire pack at once.
or shake!
! Mt. Vesuvius ! Erupted violently August 24, 79 AD ! Molten debris engulfed the surrounding area. ! Suffocating the inhabitants of the neighboring
Roman cities of Pompeii, Herculaneum and Stabiae. ! The cities remained buried and undiscovered for
almost 1700 years until excavated. ! These excavations continue today and provide
insight into life during the Roman Empire
! Mt. Vesuvius ! The eruption claimed many lives. Many of the
inhabitants were preserved under the volcanic debris.
! Mt. Vesuvius ! Millions currently live next to this active volcano.
! Mt. Vesuvius ! Millions currently live next to this active volcano.
! The cataclysmic explosion of Krakatoa was heard as far away as Western Australia, about 1,930 miles. ! 36,417 (official toll) people died. ! 13,000 times the yield of the atomic bomb that
devastated Hiroshima, Japan.
Copyright © 2010 Ryan P. Murphy
K r a k a t o a w a s h e r e .
! Pyroclasitc flow: A fast-moving avalanche of hot lava fragments.
Copyright © 2010 Ryan P. Murphy
! Pyroclastic rock: Rock ejected from a volcano. (Volcanic Bombs)
Copyright © 2010 Ryan P. Murphy
! Lahar: A flow of volcanic ash and water.
Copyright © 2010 Ryan P. Murphy
! A lahar is often produced when a snow-capped volcano erupts and hot pyroclastics melt a large amount of snow or ice.
Copyright © 2010 Ryan P. Murphy
Snowmelt mixed with ash
Crater
A crater is a steep walled depression located at the summit of a volcano. A crater can also be produced by a meteorite impact.
Acid lakes
Sulfuric acid and
hydrogen chlorides
CraterCaldera
A caldera is a large depression in a volcano formed either by the collapse of the top of a composite volcano after an explosive eruption, or from the collapse of the top of a shield volcano after the magma chamber is drained.
Crater Lake
What are the purpose of Volcanoes?
31
! New Land is formed.
Copyright © 2010 Ryan P. Murphy
! Release of healthy gases.
Copyright © 2010 Ryan P. Murphy
Water and
Carbon Dioxide
! Volcanic ash fertilizes land.
Copyright © 2010 Ryan P. Murphy
! Volcanic eruptions formed oceans and early atmosphere.
Copyright © 2010 Ryan P. Murphy
