EARTHQUAKES

Earthquakes

The study of earthquakes is seismology.

• seismographs - instruments that read earthquake waves
  • A weight is suspended from a support attached to bedrock
  • The inertia of the weight keeps it stationary while the Earth and support vibrate
  • The movement is recorded on a rotating drum creating a seismogram

Waves

• Surface waves - waves that travel along the outer layer of the Earth
  • Slowest of the waves
  • Up and down, side to side in a horizontal plane
  • Cause the greatest amount of damage
  
• Body waves - waves that travel through the Earth's interior
  • P waves (primary)
    • push-pull waves
    • Compress and expand rocks in the direction the wave is traveling
    • Travels through all materials
    • Fastest type of wave
  • S waves (secondary)
    • Shake the Earth at right angles to their direction of travel
    • Will not transmit through fluids
• Epicenter - the location on the surface directly above the focus
  • The speed of the waves can be used to determine the epicenter
  • The farther the station, the greater the time between wave arrivals