Magnitude and Energy of Earthquakes

Abstract

In a paper presented at a meeting of the Seismological Society of America on April 29, 1955, we have revised previous work on the relation of earthquake magnitude M to energy E (in ergs). Methods formerly used to extend the magnitude scale for local earthquakes to teleseisms lead to inconsistencies, so that in effect three different magnitude scales are in use: (1) M_L, the magnitude originally defined by Richter for local earthquakes in California as recorded on standard torsion seismometers. (2) M_S, that based on calculated ground amplitudes for surface waves of periods of about 20 sec. in shallow teleseisms. (3) M_B, that based on the amplitude/period ratio in body waves for both shallow and deep earthquakes.

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