What magnitude types does SCSN use?
Mw: Our preferred magnitude type, for local earthquakes 4.0 or larger, is moment magnitude Mw. Moment tensor software runs automatically on the real-time system & Mw may be inserted automatically if it passes quality criteria, or it may be inserted later by a seismic analyst. Note that a new earthquake may come up on the Recent Earthquakes maps with its ML, which may be replaced in a few minutes by the Mw, sometimes changing the number slightly. For large historical earthquakes, the Mw inserted into the catalog is usually the Harvard moment tensor solution. ML: Lacking Mw, we currently use local magnitude ML for our local earthquakes. We require several good amplitude readings on at least two stations ,however, so ML does not usually work well below about ML2.0. Prior to 1990, ML’s were generated only based on the actual Wood-Anderson seismometers, so they were generally limited to earthquakes above about ML2.5 due to the relatively small number of stations so instrumented. Mh: For cur
