How We Perceive Earthquakes (i.e Intensity)

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