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