Moment magnitude scale Moment magnitude scale The moment magnitude scale (MMS; denoted as M" or M") is one of many seismic magnitude scales used to measure the size of earthquakes. The scale was developed in the 1970s to succeed the 1930s-era Richter magnitude scale ("M"). Even though the formulas are different, the new scale was designed to produce magnitude values for a given earthquake similar to those produced by the older one. Under suitable assumptions, as with the Richter magnitude scale, an increase of one step on this logarithmic scale corresponds to a 10 (about 32) times increase in the amount of energy
Magnitude (astronomy) by astronomers are: The difference between these concepts can be seen by comparing two stars. Betelgeuse (apparent magnitude 0.5, absolute magnitude −5.8) appears slightly dimmer in the sky than Alpha Centauri (apparent magnitude 0.0, absolute magnitude 4.4) even though it emits thousands of times more light, because Betelgeuse is much farther away. Under the modern logarithmic magnitude scale, two objects, one of which is used as a reference or baseline, whose intensities (brightnesses) measured from Earth in units of power per unit area (such as watts per square metre, W m) are and , will have magnitudes and related by