Charles Francis Richter in southern California. Since 1935, several other magnitude scales have been developed. Richter was an active and avowed naturist. He travelled to many nudist communities with his wife. At his retirement party, a group of colleagues at Caltech, called the "Quidnuncs," played and sang a ditty titled "Richter Scale," which gave examples of earthquakes in American history, told in ballad style. Richter was not amused, however; he was furious. The author of the song, Kent Clark, stated in a 1989 interview that Richter enjoyed the song. The song is played on the Dr. Demento show occasionally. Richter died of congestive
Seismic magnitude scales times. As originally defined by m was based on the maximum amplitude of waves in the first 10 seconds or more. However, the length of the period influences the magnitude obtained. Early USGS/NEIC practice was to measure on the first second (just the first few P-waves), but since 1978 they measure the first twenty seconds. The modern practice is to measure short-period scale at less than three seconds, while the broadband scale is measured at periods of up to 30 seconds. The regional mb scale – also denoted mb_Lg, mbLg, MLg (USGS), Mn, and m – was developed by for