Seismic waves

• Lag time


  The delay between P waves and S waves arriving after an earthquake
• P waves are faster than S waves


  P waves arrive first following an earthquake
• Lag time


  Can be used to calculate the distance to the earthquake from that point
• Using data to find the earthquake location

  1. Convert lag time into a distance

  2. Draw circles with radius equivalent to distance

  3. Find point where circles meet
• Seismic waves


  • Primary waves (P waves)
  • Secondary waves (S waves)
  • Surface waves
• P waves


  Longitudinal, fastest, can travel through solid and liquid rock
• S waves


  Transverse, slower, can only travel through solid rock
• Surface waves


  Longitudinal, slowest, can only travel along the Earth's surface
• Earthquake at X


  Creates all three types of seismic waves
• P waves reach the opposite side of the Earth from X


  Outer core must be liquid as S waves cannot travel through it
• Seismic wave paths


  1. A: Surface wave, travels on surface

  2. B: P and S waves, travel through solid mantle

  3. C: P and S waves, travel through solid mantle

  4. D: P waves only, travel through liquid outer core

  5. E: P waves only, travel through liquid outer core