Earthquake duration magnitude - is referred to as "earthquake duration". It is this concept that Bisztricsany first used to develop his Earthquake Duration Magnitude Scale employing surface wave durations. In 1965, Solovev proposed the use of total duration instead of the duration of surface waves. In 1972, Lee et al. used coda duration for the first time to estimate Richter magnitude of local Californian earthquakes. Based on their study, they suggested that it is appropriate to estimate the magnitude of local earthquakes using signal duration. More recently, the development in instrumentation led to the use of signal duration to estimate the coda magnitude
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