When was the Richter scale first published?

Richter’s earthquake magnitude method was first published in 1935, giving scientists a standard way to compare local earthquakes. The scale used the amplitude of seismic waves measured at a specific distance from the epicenter. Although people often still say “Richter scale” for any earthquake, seismologists now prefer more modern magnitude scales for large events. The 1935 publication remains a milestone in geophysics.