In a listing of earthquakes, what do the different letters after the magnitude mean?
There are different ways of measuring magnitude and each way is notated with its own abbreviation: Mw – estimates of the seismic moment Mb – maximum amplitudes of teleseismic body waves Ms – surface waves Ml – local recordings Md – signal duration The USGS website has a FAQs section that answers some common questions about earthquakes and how they are measured.
