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EARTHQUAKES

B48a. EARTHQUAKES. Shaking Crust. EARTHQUAKES. vibrations produced by breaking of lithosphere (crust and upper mantle) elastic limit = amount that rocks can stretch and bend When surpassed --> rocks break and move seismic waves (vibrations) sent out in all directions. FAULT.

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EARTHQUAKES

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  1. B48a EARTHQUAKES Shaking Crust

  2. EARTHQUAKES • vibrations produced by breaking of lithosphere (crust and upper mantle) • elastic limit= amount that rocks can stretch and bend • When surpassed --> rocks break and move • seismic waves (vibrations) sent out in all directions

  3. FAULT • surface along which rocks move (B7, Figure 19)

  4. FOCUS- point below the surface where rocks actually break EPICENTER- point on surface directly above the focus FOCUS V. EPICENTER (B7, Figure 20)

  5. Body Waves primary secondary travel through the earth Surface Waves travel on the earth SEISMIC WAVES (B7, Figure 21)

  6. P wave move out from focus longitudinal wave particles move parallel to wave direction fastest least destructive PRIMARY SEISMIC WAVES (B7, Figure 22)

  7. S wave move out from focus transverse wave particles move at right angles to wave direction slower than P waves more destructive than P SECONDARY SEISMIC WAVES (B7, Figure 23)

  8. L wave move out from epicenter particles move in ellipses compared to wave direction slowest Most destructive SURFACE WAVES (B7, Figure 24)

  9. LAG TIME= difference between first S wave and first P wave arrival at a seismic station longer lag time = further from epicenter LAG TIME (B9, Figure 25)

  10. compares distance from epicenter to lag time TIME-TRAVEL GRAPH (B9, Figure 26)

  11. triangulation use information from at least three seismic stations Draw 3 circles Intersection = epicenter LOCATING AN EPICENTER (B9, Figure 27)

  12. Measures amount of energy released Increase of “1” = 10 times more energy released OBJECTIVE SCALE Not influenced by other factors Used to compare earthquakes RICHTER SCALE

  13. Measures amount of damage done to man-made structures SUBJECTIVE SCALE Influenced by many factors (height of buildings, age, how built, etc.) Used to determine amount of $ for aid MERCALLI SCALE

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