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Earthquakes

Earthquakes. Earth shaking. Basic Earthquake Words: The epicenter and focus. An Earthquake is the group of waves that spread away from the focus. Force pushing. Force pushing. Fault is a crack That forms Along the break.

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Earthquakes

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  1. Earthquakes Earth shaking

  2. Basic Earthquake Words: The epicenter and focus An Earthquake is the group of waves that spread away from the focus Force pushing Force pushing Fault is a crack That forms Along the break

  3. Earthquakes require a brittle-solid that breaks – the lithosphere- force builds but no shape changing shape, not plastic- break/shatters when force large enough- Earth material (rock) goes twang, energy released as earthquake waves Lithosphere: (plate) brittle solid, strong earthquakes Mantle: plastic – oozes Outer Core: liquid Inner Core: solid

  4. Earthquakes are concentrated around plate boundaries Depth of Focus: 0-70 km 70-300 km 300-700 km Plates

  5. • Pressure, Primary (P) waves: - squeeze - slinky push-pull - faster than sideways wave in Earth - travels through solids and liquids - Ex: sound only pressure wave • Sideways, Secondary (S) waves: - rope wiggle - slower than pressure wave in Earth - travels through solids, NOT liquids • Solids transmit P and S waves - Sudden force in a solid makes P and S together, usually cannot separate - Example: smack board with hammer Earthquakes Exist In the Form of Waves: Most expressed are P & S (Garrison, 1993)

  6. Actually, there are three types of Earthquake waves P=Pressure wave Slinky push-pull, Caterpillar scrunch Fastest, 1st to arrive S=Shear wave Sideways wiggle Slinky sideways wiggle Rope wiggle Slower, 2nd to arrive Surface Wave Only travels on a surface, Maximum movement on surface, Movement decreases away from surface, Movement disappears far enough away from surface Slowest, 3rd to arrive Causes Most of the Damage 2 Flavors Of Surface waves

  7. An earthquake in lithosphere (plate) makes P, S and Surface wavesthat spread outward in all directions Surface Waves Only travel On the surface = focus If the Earth were uniform, stronger P and S waves would travel inside in straight lines through the entire Earth.

  8. Seismometer Recording of an Earthquake:A record of the winners of a race with P arriving first, S second, Surface last

  9. P & S waves inside the Earth - do not travel in straight lines- take differentroutes Can’t Be Observed Explanation requires A Non-uniform Earth

  10. The San Andreas Fault: Our nearest plate boundary

  11. Lakes.                                                           <>

  12. Japan’sEarthquakes

  13. The End

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