Seismic Moment

The Seismic Moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment, is defined by the equation `M_0=muAD`, where:

• `mu` = shear modulus of the rocks used involved in the earthquake
• `A` = area of the rupture along the geologic fault where the earthquake occurred
• `D` = average displacement on A

The seismic moment of an earthquake is typically estimated using whatever information is available to constrain its factors. For modern earthquakes, moment is usually estimated from ground motion recordings of earthquakes known as seismograms. For earthquakes that occurred in times before modern instruments were available, moment may be estimated from geologic estimates of the size of the fault rupture and the displacement.

References

Wikipedia (https://en.wikipedia.org/wiki/Seismic_moment)