FAQ - Measuring Earthquakes

Q: What is moment magnitude?

A: Moment is a physical quantity proportional to the slip on the fault times the area of the fault surface that slips; it is related to the total energy released in the EQ. The moment can be estimated from seismograms (and also from geodetic measurements). The moment is then converted into a number similar to other earthquake magnitudes by a standard formula. The result is called the moment magnitude. The moment magnitude provides an estimate of earthquake size that is valid over the complete range of magnitudes, a characteristic that was lacking in other magnitude scales.

For further information, see:
Magnitudes
Intensity

« Previous FAQ | All FAQ's | All FAQ Categories | Next FAQ »