Charles Francis Richter developed a logarithmic scale to measure intensity. The name "magnitude" for this measurement came from Richter's childhood interest in astronomy - astronomers measure the intensity of stars in magnitudes. Gutenberg's contribution was substantial, but his aversion to interviews contributed to his name being left off the scale. After the publication of the proposed scale in 1935, seismologists quickly adopted it for use in measuring the intensity of earthquakes. Richter remained at the Carnegie Institute until 1936, when he obtained a post at the California Institute of Technology, where Beno Gutenberg worked. Gutenberg and Richter published "Seismicity of the Earth" in
Moment magnitude scale band. To simplify this calculation, he noted that the lowest frequency parts of the spectrum can often be used to estimate the rest of the spectrum. The lowest frequency asymptote of a seismic spectrum is characterized by the seismic moment, . Using an approximate relation between radiated energy and seismic moment (which assumes stress drop is complete and ignores fracture energy), (where E is in Joules and is in Nformula_4m), Kanamori approximated by The formula above made it much easier to estimate the energy-based magnitude , but it changed the fundamental nature of the scale into a moment magnitude scale.