See Moment (of earthquakes).
a numerical means of measuring an earthquake's total energy release. It is calculated by measuring the total length of fault rupture and then factoring in the depth of rupture, total slip along the rupture, and the strength of the faulted rocks.
a parameter related to the angular leverage of the forces that produce slip on a fault; determined from the seismic waves and field measurements that describe the fault area.
A measure of the size of an earthquake based on the area of fault rupture, the average amount of slip, and the force that was required to overcome the friction sticking the rocks together that were offset by faulting. Seismic moment can also be calculated from the amplitude spectra of seismic waves.
A measure of the strength of an earthquake, equal to the product of the force and the moment arm of the double-couple system of forces that produces ground displacements equivalent to that produced by the actual earthquake slip. It is also equal to the product of the rigidity modulus of the Earth material, the fault surface area, and the average slip along the fault. Therefore, both seismological and geological observations can produce the same result.
Seismic moment is a quantity used by earthquake seismologists to measure the amount of energy released by an earthquake.