EARTHQUAKES, SEISMIC WAVES,

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EARTHQUAKES, SEISMIC WAVES, MONITORING SYSTEMS
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Earthquake

• Shaking and trembling from movement of the
  Earths plates
• More than 8,000 quakes everyday
• Focus-point where earthquake begins
• Epicenter- point on Earths surface above the
  focus

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Seismic Waves

• Carry energy away from the earthquake
• P wave 1st waves and they compress and expand
• S wave secondary waves and they vibrate side to
  side
• Surface wave travel on the surface and produce
  ground movement

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• P-wave
• S-wave

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Measuring Earthquakes

• Mercalli Scale- measures the amount of damage on
  a scale of 1-12

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Measuring Earthquakes (2)

• Richter scale-measures an earthquakes magnitude
  (strength)
• Seismograph- measures wave strength

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Measuring Earthquakes (3)

• Movement Magnitude Scale estimates the total
  energy released by the earthquake

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Comparing Magnitudes

• One-point increase in magnitude represents 32
  times as much energy as the one before

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Locating the Epicenter

• Seismic waves are used. P waves travel faster
  than S waves

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Locating the Epicenter
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The Modern Seismograph

• Seismic waves cause a drum to vibrate while an
  attached pen records the vibrations

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Instruments to Monitor Faults (Predicting
Earthquakes)

• Tiltmeters- measures the raising of the ground
• Creep Meters- a wire measures horizontal movement
  of the ground

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More Instruments

• Laser-Ranging Devices a laser detects horizontal
  fault movements
• GPS satellites Monitor changes in elevation and
  hroizontal movements with satellites

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Mapping Faults

• Scientists study faults and the movement along
  them
• Friction- force that opposes motion of one object
  sliding over another object

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Predicting Earthquakes

• Scientists use their monitoring tools and fault
  maps to make predictions but there is no
  effective early warning system