Magnitude and energy of earthquakes

Discrepancies arise among magnitudes as derived from local earthquake data (ML), body waves (MB) and surface waves (MS). The relation of ML to the others is as yet not definitive; but MS – mB = a (MS – b). The latest revision gives a = 0.37, b = 6.76. Pending further research it is recommended that ML continue to be used as heretofore, but MS (and ultimately ML) should be referred to mB as a general standard, called the unified magnitude and denoted by m. Tentatively log E = 5.8 + 2.4 m (E in ergs). Revised tables and charts for determining m are given.