Moment magnitude scale released, and an increase of two steps corresponds to a 10 (1,000) times increase in energy. Thus, an earthquake of "M" of 7.0 releases about 32 times as much energy as one of 6.0 and nearly 1,000 times one of 5.0. The moment magnitude is based on the seismic moment of the earthquake, which is equal to the shear modulus of the rock near the fault multiplied by the average amount of slip on the fault and the size of the area that slipped. Since January 2002, the MMS has been the scale used by the United States Geological Survey
Moment magnitude scale band. To simplify this calculation, he noted that the lowest frequency parts of the spectrum can often be used to estimate the rest of the spectrum. The lowest frequency asymptote of a seismic spectrum is characterized by the seismic moment, . Using an approximate relation between radiated energy and seismic moment (which assumes stress drop is complete and ignores fracture energy), (where E is in Joules and is in Nformula_4m), Kanamori approximated by The formula above made it much easier to estimate the energy-based magnitude , but it changed the fundamental nature of the scale into a moment magnitude scale.