Earthquake Hazard: 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