Unit 4 Dynamic Earth Processes Volcanoes

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Unit 4 Dynamic Earth ProcessesVolcanoes
Earthquakes

• Earth Sci 3d
• Students know why and how earthquakes occur and
  the scales used to measure their intensity and
  magnitude
• Earth Sci 3e
• Students know there are 2 kinds of volcanoes one
  kind with violent eruptions producing steep
  slopes and the other kind with voluminous lava
  flows producing gentle slopes

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Volcano

• What is it?
• A hill or mountain formed when molten rock
  (magma) comes to Earths surface
• Magma reaching the surface is called lava

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2 Types of Volcanoes

• 1. Explosive Eruptions
• 2. Non-explosive Eruptions
• The silica content of magma helps determine
  whether the volcanic eruption is explosive or
  quiet.
• Silica is the material formed from silicon
  oxygen

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Explosive Eruption
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Explosive Eruption Volcano

• 1. Cinder Cone Volcano
• Has steep slope
• Build from various materials
• Ash
• Cinders
• Glass
• Lava fragments
• Rocks

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Explosive Eruption Volcano

• 2. Composite Volcano
• Most common type
• Has steep slope
• Explodes both lava ash
• Has alternating layers of lava, ash mud

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Composite Volcano
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Non-Explosive Eruption
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Non-Explosive Eruption Volcano

• Shield Volcano
• Built from layers of basaltic lava
• Basalt dark, fine-grained volcanic rock
• Not very steep gentle slopes
• Ex Hawaiian Islands

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What causes volcanoes?

• The formation of magma
• Mantle rock melts when the temperature increases
  or the pressure decreases

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What causes volcanoes?

• Where do volcanoes form?
• Tectonic Plate Boundaries!!!!

Ring of Fire
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What causes volcanoes?
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What causes volcanoes?

• Hot Spots

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Earthquake
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Earthquake

• Why How it occurs
• Earths crust movement causes the stresses
  applied
• These stresses can cause rocks to bend and
  stretch
• Eventually rocks will break away from one another
• Area in which the rocks break and move is called
  a fault
• Vibrations produced is called an earthquake

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Measuring Earthquakes

• Seismology
• Use instruments called seismographs
• Record seismic waves
• The height (amplitude) of the lines are used to
  measure the energy released from the earthquake
  called the magnitude
• Magnitude
• Usually determines the strength of the break
• Is measured using the Richter scale

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Seismograph
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Tsunami

• Caused by the movement of the ocean floor
• An earthquake in a subduction zone can cause
  tsunami
• When the stress reached the point where the
  overlying plate could no longer bend without
  breaking, it snapped and jerked upward.

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Tsunami
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Videos

• Volcano
• http//video.nationalgeographic.com/video/player/e
  nvironment/environment-natural-disasters/volcanoes
  /volcanoes-101.html
• Earthquake
• http//video.nationalgeographic.com/video/player/e
  nvironment/environment-natural-disasters/earthquak
  es/earthquake-101.html
• Tsunami
• http//www.youtube.com/watch?vw3AdFjklR50