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Earthquakes

Earthquakes. How they happen and what we can learn from them. What causes most earthquakes on Earth?. 1) Stress  pressure is applied to sections of rock in different directions 2) Strain  rocks deform from their original shape 3) Fracture  rocks break

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Earthquakes

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  1. Earthquakes How they happen and what we can learn from them.

  2. What causes most earthquakes on Earth? 1) Stress pressure is applied to sections of rock in different directions 2) Strain rocks deform from their original shape 3) Fracture rocks break 4) Faulting rocks move along the break as they ‘snap’ back to their original shape

  3. Q1: The description of how earthquakes happen given on the previous slide is often referred to as… • Plate Tectonic Theory • General Relativity Theory • Special Relativity Theory • Elastic Rebound Theory • Mohorovicic Discontinuity Theory

  4. Elastic Rebound Theory

  5. Q2: Which option gives the correct name for each of the letters on the diagram? • A = Focus; B = Epicenter C = Fault • A = Epicenter; B = Focus C = Fault • A = Fault; B =Focus C =Epicenter • None of these A B C

  6. When energy is released from a focus, it propagates out from that point through the interior of the Earth as two different types of waves.

  7. When the P & S waves reach the epicenter, they produce surface waves, called…

  8. Q5: Which type of earthquake wave is able to pass through liquid layers of earth’s interior—thus helping us figure out earth’s structure? • P waves • S waves • Raleigh waves • Love waves

  9. How we know about earth’s interior: • Waves refract (thus changing the timing and positioning of their arrival) when encountering a different density layer. • S-waves cannot pass through the liquid outer core.

  10. Q6: What is this? • Richter Scale • Seismograph • EKG Device • Quakemeter • None of these

  11. A Siesmograph… • Uses inertia to measure the amount of shaking experienced. • 3 different ones needed to record shaking in all directions.

  12. Q7: A Siesmogram sheet shows that… • The p-wave arrives before the s-wave • The s-wave arrives before the p-wave • Both p & s waves arrive at the same time

  13. P-wave = primary wave—travels fastest S-wave = Secondary wave

  14. Q8: Since we know how fast each type of wave travels, the amount of time between the arrival of the p-wave and the arrival of the s-wave will indicate… • The magnitude of the earthquake • How far away the epicenter is located • The exact location of the epicenter • How destructive the earthquake was • How long the earthquake lasted

  15. Since you only can tell distance to the epicenter from once siesmograph, the only thing you can do is plot that value as a circle. At least three recording stations are needed to pinpoint the exact epicenter.

  16. Q9: How does a magnitude 7 earthquake compare to a magnitude 6 earthquake? • It is 2 percent stronger • It is 10 percent stronger • It is 31 percent stronger • It is 2 times stronger • It is 10 times stronger • It is 31 times stronger

  17. Richter Scale magnitudes are logarithmic values, thus increasing from a magnitude 6 to a 7 is actually 31 times greater in terms of energy. • The Richter Scale is a logarithmic scale of wave amplitude (meaning that going from a 6 to a 7 is a 10X increase in amplitude). M5 M6 M7

  18. Oakland, CA 1989

  19. Landers, CA 1992

  20. Liquefaction Niigata, Japan 1964

  21. Landslide caused by an earthquake: Turnnagin Heights,Alaska,1964

  22. Loma Prieta, CA 1989

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