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