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Earthquakes!

Learn about earthquakes, their causes, and the different types of seismic waves. Discover how scientists locate earthquakes and measure their intensity. Explore the formation of tsunamis and the importance of tsunami warning systems.

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Earthquakes!

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  1. Earthquakes! **Adapted from www.middleschoolscience.com

  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 magma 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, break, and/or move

  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) • PUSH-PULL PATTERN! • A type of seismic wave that pushes & pullsthe ground • The FIRST wave to arrive from an earthquake—travels the fastest! • Travels Parallel to the direction the wave travels 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 (perpendicular) to the direction the wave travels • Slower! • More destructive to buildings http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

  11. Comparing Seismic Waves **P & S Wave song: http://www.youtube.com/watch?v=w3NLexYxR7g

  12. Surface Waves • Move along the Earth’s surface • ROLL OUT! Motion can be up and down, around & back & forth • Travel more slowly than S and P waves • Last to arrive • Most destructive to structures

  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. How are Earthquakes Measured? Richter Scale

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

  19. Earthquake Waves & Earth’s Interior **See how seismic waves move through the Earth’s layers here (Shadow zone): http://www.classzone.com/books/earth_science/terc/content/visualizations/es1009/es1009page01.cfm

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

  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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