On the Richter scale, the magnitude of an earthquake is related to the released energy E in joules (J) by the equation
The 1906 San Francisco earthquake registered 8.2 on the Richter scale. Using the above equation, the released energy was
Or, using the British Engineering System, the released energy was
The Richter Scale is often misunderstood by individuals. In most cases, this is a result of
having little or no understanding of the logarithmic nature of the scale. For example, what
does a difference in magnitude of 1 make in the released energy? If we consider two earthquakes, one
of magnitude M1 and another of magnitude M1 + 1, we get
An interesting web site on earthquakes is the USGS Earthquake Information site. In particular, this site has a map of the recent earthquakes in California.
The following table gives the released energies of earthquakes of magitudes 1 up to 9 in increments of 0.5. This table illustrates the exponential growth of the power of an earthquake.