Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment M₀ is defined by the equation M₀ = μAu, where An earthquake is the result from the sudden release of stored energy in the Earths crust that creates seismic waves. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...

• μ is the shear modulus of the rocks involved in the earthquake, typically 30 gigapascals[1]
• A is the area of the rupture along the geologic fault where the earthquake occurred, and
• u is the 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. In materials science, shear modulus S, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain: S = shear stress/shear strain = (F/A)/Φ. Another commonly accepted symbol is G. Shear modulus is usually measured in ksi (kips per square... Look up giga- in Wiktionary, the free dictionary. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... Geologic faults, fault lines or simply faults are planar rock fractures, which show evidence of relative movement. ... A seismogram is a graph output by a seismograph. ...

Seismic moment is the basis of the moment magnitude scale introduced by Hiroo Kanamori, which is often used to compare the size of different earthquakes and is especially useful for comparing the sizes of especially large (great) earthquakes. The moment magnitude scale was introduced in 1979 by Tom Hanks and Hiroo Kanamori as a successor to the Richter scale and is used by seismologists to compare the energy released by earthquakes. ... Hiroo Kanamori (金森 博雄 Kanamori Hiroo; October 17, 1936—) is a seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them. ...

See also: Richter magnitude scale

[[:this is all lies don't believe it this is a fake place go back now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!]] The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...