Do Now

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Do Now In Notebooks

• What are some effects of earthquakes?
• Why is intensity not always the same as magnitude
  for an earthquake?

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Earthquake Hazards
How can earthquakes affect society?
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Structural Failure

• Stone and concrete
• Easily damaged
• Wooden structures
• Withstand Earthquakes Better
• Steel-framed buildings
• High rises are reinforced to make them earthquake
  resistant

4
Structural Failure

• Pancaking
• Supporting walls of a building fail and an intact
  level above falls

5
Aftershocks

• A ground tremor caused by the repositioning of
  rocks after an earthquake

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Land and Soil Failure

• Massive landslides
• Earthquakes liquefy surface materials which then
  behave like quicksand
• Greatest damage in soft soil

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Earthquake Evidence

• Fault scarps
• Areas of great vertical offset

8
Tsunami

• A tsunami is a series of water waves generated by
  a disturbance in the ocean.

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How do Tsunamis form?

• Tsunami sources displace water in the ocean
• Gravity then acts to restore displaced water
• A wave is generated that travels as an expanding
  ring across the oceans surface

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Earthquake Forecasting

• Calculating the probability of an earthquake
• Done by following
• History of Earthquakes in an area
• Rate at which strain builds up in the rocks

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Where do Earthquakes Occur?

• Earthquakes are not randomly distributed
• Majority of earthquakes occur along seismic belts
  (Almost 80 at Circum-Pacific Belt)
• Seismic gaps
• Place along an active fault that has not
  experienced an earthquake for a long time

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