Richter magnitude scale magnitude (M) and body wave magnitude (M) scales. The Richter scale was defined in 1935 for particular circumstances and instruments; the particular circumstances refer to it being defined for Southern California and "implicitly incorporates the attenuative properties of Southern California crust and mantle." The particular instrument used would become saturated by strong earthquakes and unable to record high values. The scale was replaced in the 1970s by the moment magnitude scale (MMS, symbol ); for earthquakes adequately measured by the Richter scale, numerical values are approximately the same. Although values measured for earthquakes now are formula_1 (MMS), they are frequently
Richter magnitude scale corrections, in that for distances less than 200 kilometers the attenuation is strongly affected by the structure and properties of the regional geology. When Richter presented the resulting scale in 1935 he called it (at the suggestion of Harry Wood) simply a "magnitude" scale. "Richter magnitude" appears to have originated when Perry Byerly told the press that the scale was Richter's, and "should be referred to as such." In 1956 Gutenberg and Richter, while still referring to "magnitude scale", labelled it "local magnitude", with the symbol , to distinguish it from two other scales they had developed, the surface wave