Earthquake intensity

Macroseismic Map of the Dudley Earthquake of 2002

Intensity is a measure of an earthquake determined from the observed effects, especially damage.

For a given earthquake, intensity normally decreases with distance from the epicentre.

The observations can then be compiled to make macroseismic maps showing lines of equal intensity.

European Macroseismic Intensity Scale

  1. Not felt — detected by seismic instruments only
  2. Very weak — felt by very few people
  3. Weak — felt by a few people indoors
  4. Noticed by many people, windows and doors rattle
  5. Strong — some small objects fall over
  6. Slightly damaging — objects fall off shelves
  7. Damaging — parts of chimneys fall
  8. Very damaging — large cracks in walls
  9. Destructive — some houses collapse
  10. Very destructive — many houses collapse
  11. Devastating — most ordinary buildings collapse
  12. Completely devastating — practically all structures above and below ground are heavily damaged or destroyed