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Earthquakes

Earthquakes. What is an earthquake?. Used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip Caused by volcanic or magmatic activity, Caused by other sudden stress changes in the earth. Three Types of Faults. Strike-Slip.

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Earthquakes

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  1. Earthquakes

  2. What is an earthquake? • Used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip • Caused by volcanic or magmatic activity, • Caused by other sudden stress changes in the earth.

  3. Three Types of Faults Strike-Slip Thrust Normal

  4. What causes earthquakes? • Tectonic plates move past each other causing stress. Stress causes the rock to deform • Plastic deformation – does not cause earthquakes • Elastic deformation – rock stretches then reaches a breaking point, releasing energy.

  5. Elastic Rebound – deformed rock goes back to its original shape http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  6. Focus – point inside the Earth where an earthquake beginsEpicenter – point on Earth’s surface above focus

  7. How Seismographs Work the pendulum remains fixed as the ground moves beneath it http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  8. Typical Seismogram http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

  9. Primary Waves (P Waves) • A type of seismic wave that compresses and expands the ground • The first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

  10. Secondary Waves (S Waves) • A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

  11. Comparing Seismic Waves

  12. Surface Waves • Move along the Earth’s surface • Produces motion in the upper crust • Motion can be up and down • Motion can be around • Motion can be back and forth • Travel more slowly than S and P waves • More destructive

  13. How do scientists calculate how far a location is from the epicenter of an earthquake? • Scientists calculate the difference between arrival times of the P waves and S waves • The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

  14. How are Earthquakes Measured? Richter Scale

  15. How are Earthquakes Measured? Mercalli Intensity Scale Click Link for Interactive Demo http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

  16. Tsunamis http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  17. Formation of a tsunami http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

  18. Tsunami Warning System http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

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