If one introduces the concept of energy of an earthquake then that is a theoretically derived quantity.
Charles Francis RichterThe usual designation of the magnitude scale to my name does less than justice to the great part that Dr. Gutenberg played in extending the scale to apply to earthquakes in all parts of the world.
Charles Francis Richter[In plotting earthquake measurements] the range between the largest and smallest magnitudes seemed unmanageably large. Dr. Beno Gutenberg then made the natural suggestion to plot the amplitudes logarithmically.
Charles Francis RichterThe most remarkable feature about the magnitude scale was that it worked at all and that it could be extended on a worldwide basis. It was originally envisaged as a rather rough-and-ready procedure by which we could grade earthquakes. We would have been happy if we could have assigned just three categories, large, medium, and small; the point is, we wanted to avoid personal judgments. It actually turned out to be quite a finely tuned scale.
Charles Francis Richter