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EARTHQUAKES. Shaking Crust. EARTHQUAKES. Vibrations produced by breaking of lithosphere (crust & upper mantle) Elastic limit = amount that rocks can stretch and bend When surpassed rocks break & move Seismic waves (vibrations) sent out in all directions. Fault.

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Earthquakes

EARTHQUAKES

Shaking Crust


Earthquakes1
EARTHQUAKES

  • Vibrations produced by breaking of lithosphere (crust & upper mantle)

  • Elastic limit = amount that rocks can stretch and bend

    • When surpassed rocks break & move

    • Seismic waves (vibrations) sent out in all directions


Fault
Fault

  • Surface along which rocks move


3 types of faults
3 Types of Faults

  • Normal Thrust/Reverse Slip

    Fault Fault Fault


Focus vs epicenter
Focus vs. Epicenter

  • FOCUS – point below the surface where rocks actually break

  • EPICENTER – point on surface directly above the focus


Primary seismic waves
Primary Seismic Waves

  • P wave

  • Longitudinal wave – particles move parallel to wave direction

  • Fastest

  • Least destructive


Secondary seismic waves
Secondary Seismic Waves

  • S wave

  • Transverse wave – particles move at right angles to wave direction

  • Slower than P waves

  • More destructive than P waves


Surface waves
Surface Waves

  • L wave

  • Particles move in ellipses compared to wave direction

  • Slowest

  • Most destructive


Lag time
LAG TIME

  • LAG TIME = difference between first S wave and first P wave arrival at a seismic station

  • Longer lag time = further from the epicenter


Time travel graph
Time-Travel Graph

  • Compares distance from epicenter to lag time


Seismograph station locating an epicenter
Seismograph Station-Locating an Epicenter

  • Triangulation-information from at least 3 seismic stations

  • Seismograph measures how much the surface of the earth moves

  • Draw 3 circles

  • Intersection = Epicenter


Richter scale measures the magnitude
Richter Scale- Measures the Magnitude

  • Measures amount of energy released, magnitude

  • OBJECTIVE scale

  • NOT influenced by other factors

  • Used to compare earthquakes

  • Increase of “1” = 10 times more energy released


Mercalli scale
Mercalli Scale

  • 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


San andreas fault edge of the pacific plate is slipping past the north american plate
San Andreas Fault- edge of the Pacific plate is slipping past the North American plate



San andreas earthquake
San Andreas Earthquake

http://earthquake.usgs.gov/regional/nca/1906/18april/index.php


San andreas earthquake1
San Andreas Earthquake

http://earthquake.usgs.gov/regional/nca/1906/18april/index.php


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