Earthquakes

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Earthquakes

• A whole lotta shakin goin on.

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Focus

• Point at which there is a sudden release of
  energy below Earths surface usually along a
  fault.

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Epicenter

• Point on Earths surface directly above the focus.

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Elastic Rebound

• Stress builds along fault until the friction that
  holds the fault together is overcome.
• The fault slips.
• The deformed rocks snaps back.

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Earthquake Waves

• P-waves are push-pull waves. Compress at the
  front and expand at the rear.
• This vibration goes in the same direction that
  the wave is traveling.
• P-waves are the fastest waves.

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Earthquake Waves

• S-waves vibrate a right angles to the direction
  of travel.
• S-waves are slower than P-waves.

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Measuring Earthquake Strength

• A seismograph measures and records an
  earthquakes duration and magnitude.
• The Richter scale is a logarithmic scale.

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Earths Interior

• P and S waves give us clues to the Earth's
  interior. That no direct S waves reach the far
  side shows that the Earth's outer core is liquid.
  The size of this S-wave shadow tells us the size
  of the core.

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Black P-waves Red S-waves
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