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Earthquakes

Earthquakes. What are Earthquakes?. Earthquakes: the sudden movement of Earth’s Crust!. Where Do Earthquakes Occur?. Mostly occur near tectonic plate A break in the Earth’s crust where movement occurs is called a fault. The Three Types of Faults. Transform Boundary ( shearing ).

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Earthquakes

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  1. Earthquakes

  2. What are Earthquakes?

  3. Earthquakes:the sudden movement of Earth’s Crust!

  4. Where Do Earthquakes Occur? • Mostly occur near tectonic plate • A break in the Earth’s crust where movement occurs is called a fault.

  5. The Three Types of Faults Transform Boundary (shearing) Strike Slip Fault Convergent Boundary (compression) Reverse Fault Divergent Boundary (tension) Normal Fault

  6. What Causes Earthquakes? • Deformation of the plates! Rocks that are under stress can eventually break = EQ! • Elastic Rebound = when rocks suddenly break and spring back to their original shape. Check out the DEMO: http://projects.crustal.ucsb.edu/understanding/elastic/rebound.html

  7. How Do Earthquake Waves Travel? There are 3 types of seismic waves: • Primary Waves: P-Waves • Secondary Waves: S-Waves • Surface Waves Click Here for animation!

  8. Primary Waves (P-Waves) • Move the fastest • Move in a straight line • Compress and expand like an accordion • Move through solids, liquids, and gases

  9. P-Wave

  10. Secondary Waves (S-Waves) • 2nd fastest • Vibrate side to side and up and down • Can only move through solids

  11. S-Wave

  12. Surface Waves • Result of P-waves and S-waves when they reach the surface • Only travel in the crust! • Slowest seismic waves • Make the ground roll like ocean waves • Responsible for surface damage and falling buildings.

  13. Surface Waves Notice the top is moving more than the bottom!

  14. Surface Wave Diagram

  15. How are earthquakes measured? • Seismograph: records ground movements of earthquakes • The pendulum sits still while the ground moves. http://www.wwnorton.com/college/geo/egeo/flash/8_3.swf

  16. What is the seismograph measuring? • Epicenter: Center of earthquake ABOVE GROUND • Focus: Point where rocks break UNDERGROUND

  17. Earthquake Location

  18. Earthquake Effects - Ground Shaking Loma Prieta, CA 1989 KGO-TV News ABC-7

  19. Earthquake Effects - Ground Shaking Kobe, Japan 1995

  20. Earthquake Effects - Ground Shaking Kobe, Japan 1995

  21. Earthquake Effects - Surface Faulting Landers, CA 1992

  22. Earthquake Effects - Landslides Source: National Geophysical Data Center Turnagain Heights, Alaska,1964 (upper left inset); Santa Cruz Mtns, California , 1989

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