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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 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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