- Seismic moment
Seismic moment is a quantity used by
earthquake seismologist s to measure the size of an earthquake. The scalar seismic moment is defined by the equation, where
* is theshear modulus of the rocks involved in the earthquake, typically 30giga pascals [http://scienceworld.wolfram.com/physics/ShearModulus.html]
* is the area of the rupture along thegeologic fault where the earthquake occurred, and
* is the average displacement on .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
seismogram s. 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.Seismic moment is the basis of the
moment magnitude scale introduced byHiroo 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.:"See also":
Richter magnitude scale References
*Cite book
last=Aki
first=Keiti
coauthors=Richards, Paul G.
year=2002
title=Quantitative seismology
edition=2nd ed.
publisher=University Science Books
id=ISBN 0-935702-96-2*Cite book
last=Fowler
first=C. M. R.
year=1990
title=The solid earth
location=Cambridge, UK
publisher=Cambridge University Press
id=ISBN 0-521-38590-3
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