Earthquake Hazard: Ground Shaking

Ground Shaking

• ground shakes
• buildings and things inside may fall
• 1556 Shaanxi province, china
  • worst recorded earthquake for fatalities
  • housing was silt (very fine-grained sediment) caves, most collapsed
  • 883,000 people died
• buildings on solid rock or compacted sediments are safer
• wet, loose sediment and artificial fill have longer and more intense shaking
  • also prone to liquefaction
• shaking can trigger resonance in a building
  • amplitude of the wave increases when the frequency of the seismic wave is the same or very close to the natural frequency of the building
• hypocenter: point on the fault where motion starts
• epicenter: directly above hypocenter on surface
• when the ground shakes, it creates a fault scarp
  • fault scarp: exposure of the fault visible at the surface; exposed due to offset (movement) along the fault
• elastic rebound theory: explains how energy builds up and is then released in an earthquake and how that energy is released
  • this can create ground shaking