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EARTHQUAKES & SEISMIC WAVES

EARTHQUAKES & SEISMIC WAVES. CHAPTER 6.2. What is an earthquake?. The shaking and trembling that results from the movement of rock beneath Earth’s surface Caused by plate movement. Where does an earthquake start? .

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EARTHQUAKES & SEISMIC WAVES

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  1. EARTHQUAKES & SEISMIC WAVES CHAPTER 6.2

  2. What is an earthquake? • The shaking and trembling that results from the movement of rock beneath Earth’s surface • Caused by plate movement

  3. Where does an earthquake start? • Focus: area beneath Earth’s surface where rock that is under stress breaks, triggering an earthquake • Epicenter: point on the surface directly above the focus

  4. How does an earthquake move? • Seismic waves carry energy from an earthquake away from the focus, through Earth’s interior, and across the surface.

  5. Are there different types of seismic waves? YES!

  6. p waves • First waves to arrive • Compress and expand the ground like an accordion • Crust vibrates forward and back along the path of the wave • Can damage buildings • Travels through solids and liquids

  7. S WAVES • Secondary waves • Seismic waves that vibrate from side to side as well as up and down • Cannot travel through liquids • Shakes structures violently

  8. Moves like an accordion Moves like ‘the wave’ at a football game

  9. SURFACE WAVES • Move more slowly than P waves and S waves, but can produce severe ground movements • Can make the ground roll like ocean waves or shake buildings from side to side

  10. How are seismic waves measured? With a SEISMOGRAPH

  11. What are the 3 ways to measure an earthquake? • 1. Mercalli scale: rates the earthquakes according to level of damage at a given place (pg 191)

  12. Mercalli Scale XII in La Paz, Bolivia

  13. 2. Richter Scale: rating of an earthquake’s magnitude based on the size of the earthquake’s seismic waves • Magnitude of an Earthquake: a # that geologist assign to an earthquake based on the earthquake’s size

  14. 3. Moment Magnitude Scale: rating system that estimates the total energy released by an earthquake

  15. Geologists use the seismic waves to locate an earthquake…. EPICENTER

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