Magnitude and energy of earthquakes

Abstract

Discrepancies arise among magnitudes as derived from local earthquake data (MI), body waves (MB and surface waves (MS). The relation of ML to the others is as yet not definitive; but M S - 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 MI) 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. © 2010 by the Istituto Nazionale di Geofisica e Vulcanologia. All rights reserved.