What scales are used to measure earthquakes?
A logarithmic earthquake magnitude scale, referred to as ML was first developed by Charles Richter in the 1930’s. To take advantage of the increase in globally distributed seismograph stations, new magnitude scales that are an extension of Richter’s original idea were developed and include body-wave magnitude, Mb and surface wave magnitude, Ms. Because of limitations of all three magnitude scales, a new, more uniformly applicable extension known as moment magnitude, or Mw, was developed. In particular, for very large earthquakes moment magnitude gives the most reliable estimate of earthquake size.
