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
Logarithmic scale the value of a logarithm function. Here, a given logarithmic unit will be denoted using the notation [log "n"], where "n" is a positive real number, and [log ] here denotes the indefinite logarithm function Log(). Examples of logarithmic units include common units of information and entropy, such as the "bit" [log 2] and the "byte" 8[log 2] = [log 256], also the "nat" [log e] and the "ban" [log 10]; units of relative signal strength magnitude such as the "decibel" 0.1[log 10] and "bel" [log 10], "neper" [log e], and other logarithmic-scale units such as the Richter magnitude scale