Moment magnitude scale being constants. For instance, formula_23 depends on rupture speed; it is close to 1 for regular earthquakes but much smaller for slower earthquakes such as tsunami earthquakes and slow earthquakes. Two earthquakes with identical formula_17 but different formula_23 or formula_22 would have radiated different formula_27. Because formula_27 and formula_17 are fundamentally independent properties of an earthquake source, and since formula_27 can now be computed more directly and robustly than in the 1970s, introducing a separate magnitude associated to radiated energy was warranted. Choy and Boatwright defined in 1995 the "energy magnitude" where formula_27 is in J (N·m). Assuming the values
Seismic magnitude scales well" with the seismic moment magnitude in the range of 4.5 to 7.5, but underestimate larger magnitudes. Body-waves consist of P-waves that are the first to arrive (see seismogram), or S-waves, or reflections of either. Body-waves travel through rock directly. The original "body-wave magnitude" – mB or m (uppercase "B") – was developed by and to overcome the distance and magnitude limitations of the scale inherent in the use of surface waves. is based on the P- and S-waves, measured over a longer period, and does not saturate until around M 8. However, it is not sensitive to events smaller