Volcanoes

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Volcanoes
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(No Transcript)
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Volcano Vocabulary

• Vent
• Cone
• Magma
• Lava
• Lava bomb
• Eruption
• Crater
• Pyroclastic Material
• Viscosity
• Silicon

• 3 Types
• Shield
• Composite
• Cindercone
• Hot spot

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What is a volcano?
vent

• A volcano is a vent or 'chimney' that connects
  molten rock (magma) from within the Earths crust
  to the Earth's surface.
• The volcano includes the surrounding cone of
  erupted material.

cone
conduit
magma chamber
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The Parts of a Volcano
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What are the parts of a Volcano?

• VENT- the vent is the opening from which lava
  flows. Dust, ash, noxious gases, and rock
  particles can also be thrown out of the vent!

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• Cone Material such as lava flow, pyroclastic
  material, ash which is built up around the vent

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Magma V Lava

• Magma Under the crust
• Lava Above the crust

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Lava Bomb

• A projectile of burning lava

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• Crater funnel shaped pit at the top of a volcano
  from a previous eruption

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• Pyroclastic Material derived from Greek for Fire
  and broken rock. Usually explosive eruptions

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• Viscosity the ability for a fluid to flow. High
  viscosity means it does not flow well, and low
  viscosity means it flows easily

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Types of Volcanoes

• There are 3 types of Volcanoes
• Shield
• Cinder Cone
• Composite
• They are
• classified by
• how they form.

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Shield Volcano

• Wide and somewhat flat.
• It forms from a quiet eruption.
• Mauna Loa in Hawaii.

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Cinder Cone Volcano

• Has tall, very steep sides.
• Has explosive eruptions. Lots of Cinder and ash.
• Paricutin Corn field in Mexico, 1200 feet 1943

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Composite Volcano

• Extremely large
• Powerful explosive eruptions followed by smooth
  flow
• Mt. Rainier, Mt Fuji, and

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Mt St. Helens
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Hot Spots

• Hotspots are responsible for the formation of
  Hawaiian Islands

• Put simply, Hot spots are vents in the plates
  that erupt periodically while the plates move

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How and why do volcanoes erupt?

• Explosive eruption High viscosity, and lots of
  trapped gasses (H2O, CO2, S) Pressure builds
  until the gasses escape violently
• Effusive (Quiet) eruption Low viscosity, and
  little gasses (H2O, CO2, S) Pressure does not
  build

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Explosive Eruptions

• Three products from an explosive eruption
• Ash fall
• Pyroclastic flow
• Pyroclastic surge

Pyroclastic flows on Montserrat, buried the
capital city.
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Effusive Eruptions

• Effusive eruptions are characterised by
  outpourings of lava on to the ground.

Hawaii
Courtesy of www.swisseduc.ch
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Volcanic Hazards

• Pyroclastic flow
• Lahars/Mud flows
• Pyroclastic fall
• Lava flow
• Noxious Gas
• Earthquakes

Courtesy of www.swisseduc.ch
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Pyroclastic Flow

• For example, eruption of Vesuvius in 79 AD
  destroyed the city of Pompeii

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Pompeii (79AD)

• On August 24, 79AD Mount Vesuvius literally blew
  its top, erupting tonnes of molten ash, pumice
  and sulfuric gas miles into the atmosphere.
  Pyroclastic flows flowed over the city of Pompeii
  and surrounding areas.

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Pompeii (79AD)

• Pyroclastic flows of poisonous gas and hot
  volcanic debris engulfed the cities of Pompeii,
  Herculaneum and Stabiae suffocating the
  inhabitants and burying the buildings.

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Lava Flow

• It is not just explosive volcanic activity that
  can be hazardous. Effusive (lava) activity is
  also dangerous.

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Seismic Activity

• Earthquake activity commonly precedes an eruption
• Result of magma pushing up towards the surface
• Increase volume of material in the volcano
  shatters the rock
• This causes earthquakes

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Game

• Crossword