BE INFORMED, BE WARNED, BE PREPARED:   BEFORE, DURING and AFTER an EARTHQUAKE
 
Earthquakes in British Columbia
 
Earthquake Magnitude - The Richter Scale
 
The strength of an earthquake can also be measured and expressed in terms of the magnitude of energy released by the earthquake.
 
Seismologist Charles Richter devised his system based on the amplitude of the seismic waves recorded by seismographs. When the data from several seismometers are compared a measure of magnitude can be realized within minutes of the earthquake activity.
 
The Richter scale is logarithmic. An increase in magnitude of one unit corresponds to a tenfold increase in the size of an earthquake. Thus an earthquake of magnitude 6 is ten times larger than one of magnitude 5, and a hundred times larger than one of magnitude 4.

Richter Scale

Richter
Scale #
Earthquakes
globally per year
Typical Intensity at center
(see Mercalli Scale)
Acceleration.
% of gravity (g)
8.0 +  0.1 - 0.2  XII -
7.4 - 8.0  XI -
7.0 - 7.3 15  X 70
6.2 - 6.9  100 VIII - IX 15 - 32
5.5 - 6.1  500 VII 7
4.9 - 5.4 1,400 VI 3
4.3 - 4.8  4,800 IV-V 0.7-1.5
3.5 - 4.2 30,000  II - III  0.2 - 0.3
2.0 - 3.4 800,000  I - II 0.1 - 0.2

Copyright: A. Makarow 1998 - Revised September 17, 2008