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Earthquakes

Earthquakes. Liz LaRosa http://www.middleschoolscience.com 2009 for my 5 th grade science class 2009. What is an earthquake?. The slipping and breaking of rock material along a fault. Faults are “cracks” in the crust near plate boundaries that are under stress.

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Earthquakes

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  1. Earthquakes Liz LaRosa http://www.middleschoolscience.com 2009 for my 5th grade science class 2009

  2. What is an earthquake? • The slipping and breaking of rock material along a fault. • Faults are “cracks” in the crust near plate boundaries that are under stress. • Stress is caused by the heat within the earth trying to escape and the movement of the plates.

  3. Three Types of Faults Strike-Slip - shearing Thrust - Compression Normal – pulling away

  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 – kind of bounces back like a rubberband.

  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. Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  8. 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

  9. 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

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

  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. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  15. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

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

  17. Earthquake Waves & Earth’s Interior

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

  19. How are Earthquakes Measured? Richter Scale

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

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

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

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

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