Earthquake Magnitude Perspective

Tsunami warning center scientists usually measure an earthquake's "size" with the moment magnitude scale rather than the older but more famous Richter magnitude scale. The moment magnitude scale is better suited for measuring the "sizes" of very large earthquakes and its values are proportional to an earthquake's total energy release, making this measurement more useful for tsunami forecasting. This measurement has been used since the 1970's with the introduction of more modern broadband seismometers. To read more about the Richter vs. Moment magnitude scales, click here. or watch a video here.

Moment magnitude numbers scale such that energy release increases by a factor of about 32 for each whole magnitude number. For example, magnitude 6 releases about 32 times as much energy as magnitude 5, magnitude 7 about 32 times as much as magnitude 6, and so on.

This animation graphically compares the relative "sizes" of some 20th and 21st century earthquakes by their moment magnitudes. Each circle's area represents its relative energy release, and its label lists its moment magnitude, its location, and the year it happened.

You can view a YouTube version of this animation here.