Measuring Earthquakes

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Measuring Earthquakes
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Seismographs

• Seismograph Instrument used to measure and
  record seismic waves.

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Earliest Seismoscope
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19th Century Seismograph
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Seismograph
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Richter Scale

• Magnitude is on a logarithmic scale.
• The ground moves 10 times as much in a magnitude
  2 earthquake than a magnitude 1.
• A magnitude 3 has 100 times the shaking of a
  magnitude 1 earthquake.

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Richter Scale
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Earthquake Magnitude
M5
M6
M7
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Earthquake Severity

• Richter Earthquake
• Magnitudes Effects
• Less than 3.5 Generally not felt, but recorded.
• 3.5-5.4 Often felt, but rarely causes
  damage.
• Under 6.0 At most slight damage to
  well-designed buildings.
• Can cause major damage to poorly constructed
  buildings
• over small regions.
• 6.1-6.9 Can be destructive in areas up to
  about 100 kilometers
• across where people live.
• 7.0-7.9 Major earthquake. Can cause
  serious damage over larger areas.
• 8 or greater Great earthquake. Can cause serious
  damage in areas several
  hundred kilometers across.

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Seismographs of Today