Intensity Attenuation

1. Intensity attenuation refers to any reduction in the strength of a signal.

2. It is relatively compared with the attenuation of peak ground acceleration that is used for engineering design.

3. Knowledge of intensity attenuation is useful in calibrating hazard models against historical experience.

4. Intensity attenuation equation is given by:

I = 3.31 + 1.28 ML-1.22 In R

where

I = Intensity

ML = Local Magnitude

R = Hypocentral distance

5. As radiant energy from a point light source travels through space, its amplitude is attenuated by the factor 1d", where d is the distance that the light has traveled.

6.This means that a surface close to the light source receives higher incident intensity from the source than a distant surface.