Seismic magnitude scales based on a simple model of rupture, and on certain simplifying assumptions; it incorrectly assumes that the proportion of energy radiated as seismic waves is the same for all earthquakes. Much of an earthquake's total energy as measured by is dissipated as friction (resulting in heating of the crust). An earthquake's potential to cause strong ground shaking depends on the comparatively small fraction of energy radiated as seismic waves, and is better measured on the "energy magnitude" scale, M. The proportion of total energy radiated as seismic varies greatly depending on focal mechanism and tectonic environment; and for very similar
Absolute magnitude using an absolute magnitude, one must specify the type of electromagnetic radiation being measured. When referring to total energy output, the proper term is bolometric magnitude. The bolometric magnitude usually is computed from the visual magnitude plus a bolometric correction, . This correction is needed because very hot stars radiate mostly ultraviolet radiation, whereas very cool stars radiate mostly infrared radiation (see Planck's law). Some stars visible to the naked eye have such a low absolute magnitude that they would appear bright enough to outshine the planets and cast shadows if they were at 10 parsecs from the Earth. Examples