Seismic magnitude scales

Seismic magnitude scales are used to describe the overall strength or "size" of an earthquake.

1. 1 Earthquake magnitude and ground-shaking intensity
2. 2 Magnitude scales
   1. 2.1 "Richter" magnitude scale
   2. 2.2 Other "Local" magnitude scales
      1. 2.2.1 Japan Meteorological Agency magnitude scale
   3. 2.3 Body-wave magnitude scales
      1. 2.3.1 mB scale
      2. 2.3.2 mb scale
      3. 2.3.3 mbLg scale
   4. 2.4 Surface-wave magnitude scales
   5. 2.5 Moment magnitude and energy magnitude scales
   6. 2.6 Energy class (K-class) scale
   7. 2.7 Tsunami magnitude scales
   8. 2.8 Duration and Coda magnitude scales
   9. 2.9 Macroseismic magnitude scales
   10. 2.10 Other magnitude scales

These are distinguished from seismic intensity scalesthat categorize the intensity or severity of ground shaking (quaking) caused by an earthquake at a given location.

Seismic Magnitude Scales Media

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  Isoseismal map for the 1968 Illinois earthquake. The irregular distribution of shaking arises from variations of geology and ground conditions.

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  Differences in the crust underlying North America east of the Rocky Mountains makes that area more sensitive to earthquakes. Shown here: the 1895 New Madrid earthquake, M ~6, was felt through most of the central U.S., while the 1994 Northridge quake, though almost ten times stronger at M 6.7, was felt only in southern California. From USGS Fact Sheet 017–03.