Earthquakes

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Earthquakes
Photo credit USGS
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Where Do Earthquakes Occur?
Plate Boundaries
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Causes of Earthquakes

• Plastic Deformation
• Faults
• Normal
• Reverse
• Strike-Slip

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Types of Earthquakes
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Elastic Rebound Theory

• Explains how energy is stored in rocks
• Rocks bend until the strength of the rock is
  exceeded
• Rupture occurs and the rocks quickly rebound to
  an undeformed shape
• Energy is released in waves that radiate outward
  from the fault

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Seismic Waves

• Body Waves
• P-waves
• S-waves
• Surface Waves

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Body Waves

• Travel through the interior of the Earth
• P waves (Primary waves)
• S waves (Secondary waves)

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Primary Waves

• P waves
• fastest seismic waves
• move through solids, liquids gasses
• compressional waves (sound waves)
• compress and expand matter

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Secondary Waves

• S waves
• second-fastest seismic waves
• directly follow P waves
• move through solids, shearing rock
• travel sideways at right angles to the direction
  of motion
• more dangerous than P waves
• larger
• produce vertical and horizontal motion

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Surface Waves

• Move ground up and down in circles
• Slowest and most destructive

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Let ER Rip
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