Earthquake Effects

Primary Effects

• Short periods of intense ground motion

  • Can damage human structures

  • “Earthquakes don’t kill people, buildings kill people”

• A few factors determine the amount and intensity of damage done

  • Key factor of intensity of damage is the earthquake’s magnitude

  • Length is also important (larger earthquakes tend to be longer)

  • How buildings are structured and constructed

  • Surface materials on which structures are built

    • Structures on loose/sedimentary materials usually experience more intense shaking

    • Structures on solid rock are generally more stable

    • Some structures can be engineered specifically to mitigate earthquake damage

Secondary Effects

• Other processes related to the shaking

• Mountainous areas → landslides (loose rocks/soil break free)

• Wet, low-lying areas → liquefaction (wet soils liquify)

  • Especially common in areas of sandy soils

• Ground cracking

• Fire

  • Shaking may break gas lines, which catch fire

  • Eg. 1906 San Francisco earthquake → wooden buildings survived quake but not fire

• Tsunamis

  • Fault movements displace water above the fault

  • Waves radiate from epicenter

  • Not overly noticeable in middle of ocean, but can wreck coastal areas