Arkansas Center for Earthquake Education and Technology Transfer

The Moment Magnitude Scale

Moment Magnitude is the measure of total energy released by an earthquake. Moment magnitude is the measurement and term generally prefered by scientists and seismologists to the Richter scale because moment magnitude is more precise.

Moment Magnitude is not based on instrumental recordings of a quake, but on the area of the fault that ruptured in the quake. This means that the moment magnitude describes something physical about an earthquake. Moment Magnitude is calculated in part by multiplying the area of the fault's rupture surface by the distance the earth moves along the fault

The Moment Magnitude scale now supercedes the Richter scale.

Comparison between the Richter and Moment Magnitude Scales

Earthquake Richter Scale Moment Magnitude
New Madrid, MO, 1812 8.7 8.1
San Francisco, CA 1906 8.3 7.7
Prince William, AK 1964 8.4 9.2
Northridge, CA,1994 6.4 6.7

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U-A-L-R

Arkansas Earthquake Center
College of Science and Engineering Technology
2801 South University
Little Rock AR 72204

(501) 569-8223

Last Updated: September 2, 1998

earthquake@quake.ualr.edu

Copyright 1998, UALR
All rights reserved.

http://quake.ualr.edu/public/moment.htm