seismic moment

geophysics

Also known as: M0

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Last updated

July 13, 2026

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The moment magnitude scale (M_W) is a quantitative measure of an earthquake's size, developed to more accurately assess the total energy released. Unlike older scales like the Richter scale, which rely on seismic wave amplitudes, moment magnitude is tied to the earthquake's seismic moment (M₀).12

The seismic moment is calculated using the fault's geometry and the displacement across its surface. Specifically, it's the product of the fault area, the average slip on the fault, and the rigidity of the rocks involved: M₀ = DA\u03bc. This method avoids "magnitude saturation," allowing for reliable measurement of even the largest and most destructive earthquakes.1

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earthquake
Earthquake magnitude
…earthquake size is used—namely, the seismic moment (M₀). Such a parameter is related to the angular leverage of the forces that produce the slip on the causative fault. It can be calculated both from recorded seismic waves and from field measurements of the size of the fault rupture. Consequently, seismic…
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…earthquake size is used—namely, the seismic moment (M₀). Such a parameter is related to the angular leverage of the forces that produce the slip on the causative fault. It can be calculated both from recorded seismic waves and from field measurements of the size of the fault rupture. Consequently, seismic…
Read More