Moment magnitude scale deal with significant earthquakes larger than . For these events, the official magnitude is the moment magnitude , not Richter's local magnitude . The symbol for the moment magnitude scale is , with the subscript "w" meaning mechanical work accomplished. The moment magnitude is a dimensionless value defined by Hiroo Kanamori as where is the seismic moment in dyne⋅cm (10 N⋅m). The constant values in the equation are chosen to achieve consistency with the magnitude values produced by earlier scales, such as the Local Magnitude and the Surface Wave magnitude. Seismic moment is not a direct measure of energy changes
Orders of magnitude (length) (10 m or 1.1 billion light-years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depends on the cosmological models used. To help compare different orders of magnitude, this section lists distances starting at 100 Ym (10 m or 11 billion light years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depend on the cosmological models used. Distances longer than 100 Ym Orders of magnitude (length) The following are examples of orders of magnitude for different lengths.