Volcanoes

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Volcanoes

• by Jeremy Butkovich
• jebutkov_at_nmu.edu

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Volcanic Terms

• Volcano A mountain formed from lava and/or
  pyroclastics.
• Pyroclastics The volcanic rock fragments and
  ash ejected during an eruption.
• Magma Molten rock deep under the earths crust.
• Lava Magma that reaches the Earths surface.
• Viscosity A measure of a fluids resistance to
  flow.

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What Causes a Volcano?

• Volcanoes are generally found along fault lines.
• Friction and intense pressure between two
  Tectonic plates melt the surrounding rock.
• The molten rock and gases work their way to the
  earths surface where they form the volcano.

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What Causes a Volcano? Continued

• Hot spots, concentrations of heat in the mantle
  that produces magma which extrudes onto the
  Earths surface, is another source of Volcanoes.
• The Hawaiian islands were formed from a hot spot.

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Anatomy of a Volcano
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Types of Volcanoes

• There are several different types of Volcanoes,
  depending on the viscosity of the magma and the
  violence of the eruption.
• Shield Volcanoes
• Cinder Cone
• Composite Cone

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Shield Volcanoes
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Shield Volcanoes

• Created by very fluid low viscosity lava flows
• Very broad slightly domed structure
• Small percentage of pyroclastic materials
• Non-violent eruptions
• Example
• The Hawaiian islands

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Cinder Cones
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Cinder Cones

• Built from ejected lava fragments that take on
  the appearance of cinders as they harden while in
  flight
• Steep sided
• Composed mostly of pyroclastic material
• Moderately violent eruptions with a very short
  life span
• Example
• Paricutin

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Composite Cones
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Composite Cones

• Composed of both lava and pyroclastics
• Gas rich magma causes violent eruptions
• Most located in Pacific Ring of Fire
• Steep summits with gradually sloping flanks
• Example
• Mount Saint Helens

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Natural Hazards

• Many people live in areas near volcanoes with
  their picturesque vistas
• Mud and pyroclastic flows and can cause damage
  miles away from the volcano
• Ash spewed in the air during the eruption can
  affect populaces hundreds of miles away

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Additional Resources

• www.usgs.gov United States Geological Survey
• www.mtu.edu Michigan Technology University
  Volcanoes Page
• Mount Vesuvius Historical eruption that erupted
  unexpected and was highly documented
• Cascade Volcano Observatory Learn about
  volcanoes at this informative web site.
• San Diego State University Learn more about how
  volcanoes work and test yourself with quizzes.