Moment magnitude scale to calculate and report magnitudes for all modern large earthquakes. Popular press reports of earthquake magnitude usually fail to distinguish between magnitude scales, and are often reported as "Richter magnitudes" when the reported magnitude is a moment magnitude (or a surface-wave or body-wave magnitude). Because the scales were designed to report similar results within applicable conditions, the confusion is minor. In 1935, Charles Richter and Beno Gutenberg developed the local magnitude () scale (popularly known as the Richter scale) with the goal of quantifying medium-sized earthquakes (between magnitude 3.0 and 7.0) in Southern California. This scale was based on the
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