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Earthquake Hazards

Earthquake Hazards. Earthquakes and Society. A. Some Earthquake Hazards. Structural Failure Land and Soil Failure Fault scarps (the earth opens up!) Tsunamis- NOT tidal events. Structural Failure .

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Earthquake Hazards

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  1. Earthquake Hazards

  2. Earthquakes and Society A. Some Earthquake Hazards • Structural Failure • Land and Soil Failure • Fault scarps (the earth opens up!) • Tsunamis- NOT tidal events

  3. Structural Failure • The damage produced by an earthquake is directly related to the strength or quality of the structures involved. • The most severe damage occurs to unreinforced buildings made of stone, concrete, or other brittle building materials. • Wooden structures and many modern high-rise, steel-frame buildings sustain little damage during an earthquake.

  4. Earthquakes and Society Land and Soil Failure • Earthquakes may trigger massive landslides in sloping areas. • In areas with sandy soil, earthquakes may cause subsurface materials to shake so much they liquefy and behave like quicksand. • Wave size and earthquake intensity are amplified in soft, unconsolidated sediments and are dampened in hard, resistant rocks such as granite.

  5. Earthquakes and Society Fault Scarps • Fault movements associated with earthquakes can produce fault scarps. • Fault scarps are cliffs that form where the fault meet the ground surface.

  6. Earthquakes and Society • A tsunami is a large ocean wave generated by vertical motions of the seafloor during an earthquake. Tsunami • These motions displace the entire column of water overlying the fault, creating bulges and depressions in the water. • The disturbance spreads out from the epicenter in the form of extremely long waves that can travel at speeds of between 500 and 800 km/h • When the waves enter shallow water they may form huge breakers with heights occasionally exceeding 30 m.

  7. Earthquakes and Society B. Seismic Risk • West Coast, Alaska & Hawaii • New Madrid Zone

  8. Earthquakes and Society

  9. Earthquakes and Society C. Earthquake Prediction 1.The probability of an earthquake’s occurring is based on two factors: • The history of earthquakes in an area • The rate at which strain builds up in the rocks 2. Seismic Gap -sections of active faults that haven’t had earthquakes for a long period of time.

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