Seismicity 2

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  • Created by: Sharon
  • Created on: 30-12-15 17:14
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  • Seismicity 2
    • Short Term Prediction
      • monitoring processes signify quakes
        • Hard as  deep in surface & no patterns
      • anomalous/proced quakes "precursor"
        • Ground uplift - swelling rokcs - cracks rocks
        • Forechocks
        • Water level - pressure increases force water up or down.
        • emission radon - decay uranium, strain causes deformation and release.
        • animal behavior - snakes not in holes, panda screaming
    • Mitigating
      • "quakes don't kill, buildings do"
      • California strict building codes 1986 40 died in 7.1 Armenia no codes 25,000 died 10 months later
      • 2010 Haiti 250,000 - Feb 27 Chile where are codes only 520
      • Japan City resistent/awareness/improve prediction./evacuation routes/laws in 07/oberservation areas/spare supplies always/smart metre turns of gas/insurance just for earthquake
    • Risk
      • depends on  whether tectonic activity occurs in area.
      • US greatest, San Andreas,
      • If before likely to happen again
    • Controlling
      • No attempt control. Known to be cause by humans = possible to control
      • Hoover Dam fluid pressure = 600 quakes
      • Nuclear testing Nevada = 6.3
      • Increase magnitude = 30 fold increase energy (8.0=7.0x30)
    • Where
      • Distribution and frequency "seismicity"
      • Shallow focus - Focal depth >70km
      • Deep focus - focal 700km
      • Diverging
        • Move away/lithosphere tensional stress/shallow quakes
      • Converging
        • run into/compressional stress
          • Subduction - oceanic under continental - lithosphere cold=descend brittle=fractures=quakes
          • Collision - 2 continental collide.
    • Long term forecasting
      • Knowledge when&where have occurred.
      • Paleoseismology - prehistoric quakes, determine reoccurance intervals
      • Seismic gaps - zone along tectonically active area no quakes recently, known strain is building

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