Why are there so many earthquake magnitude scales?
Earthquake size, as measured by the Richter Scale, is a well known but not a properly understood concept. What is even less well understood is the proliferation of magnitude scales and their relation to Richters original magnitude scale? Charles Richter first developed the idea of a logarithmic earthquake magnitude scale in the 1930s for measuring the size of earthquakes occurring in southern California, using relatively high-frequency data from nearby seismograph stations. This magnitude scale was referred to as ML, with the L standing for local. This eventually came to be known as the Richter magnitude. As more seismograph stations were installed around the world, it became apparent that the method developed by Richter was strictly valid only for certain frequency and distance ranges. In order to take advantage of the growing number of globally distributed seismograph stations; new magnitude scales that are an extension of Richters original idea were developed. These include body-wav
