Intensity

• how we perceive earthquakes (the intensity we feel) depends on several factors…

  1. magnitude:

     1. lower magnitude = less intense

        1. less energy, waves less powerful

        2. shorter shaker time

  2. distance from epicenter

     1. further = less intense

        1. seismic waves attenuate (weaken) as they travel

  3. duration (how long)

     1. shorter = less intense

        1. larger earthquakes can have several minutes of shaking

  4. foundation (ground) material

     1. solid rock = least intense

     2. well-compacted sediment = less intense

     3. water-saturated sediment = more intense (potential for liquefaction)

  5. building structure (building reaction to ground acceleration)

     1. in general:

        1. brick and concrete = bad

        2. wood, steel, and reinforced concrete = good