The Richter magnitude scale was orginally developed by Charles Richter and Beno Gutenberg to make more quantitative measures of the relative sizes of earthquakes in southern California. Today, modified versions of the scale are used to measure earthquakes throughout the world.

The Richter magnitude is related to the maximum amplitude of the S wave measured from the seismogram. Because there is a great range in the sizes of different earthquakes, the Richter scale uses logarithms. Thus, a magnitude 7 (M 7) earthquake is 10 times as large as a magnitude 6 earthquake, and releases over 30 times more energy.