seismicity

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  • Created by: elizabeth
  • Created on: 20-03-14 12:38
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  • seismicity
    • causes of earthquakes
      • as the crust of the earth is mobile, there tends to be a slow build up of stress within the rocks. when the pressure is suddenly released parts of the earth experience an  intense shaking motion that lasts for a few seconds
      • focus- the point at which this pressure release occurs
      • epicentre- the point immediately above that on the earth
      • shallow focus-0-70km causes greatest damage and account for 75% of all earthquake energy released
    • distribution
      • the vast majority of earthquakes occur at fault lines some people claim however that they can be caused by humans building large reservoirs in which water puts pressure on surface rocks or subsidence of deep mine workings
    • magnitude and frequency
      • measured on 2 scales- richter and logarithmic
    • effects of earthquakes
      • primary effects- ground shaking
      • secondary effects
        • soil liquefaction
        • landslides/avalanches
        • effects on the people and built environment
        • tsunamis

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