Seismic moment is a quantity used by
earthquake seismologists to measure the size of an earthquake. The scalar seismic moment
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=2092)
is defined by the equation
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=3134)
, where
is the shear modulus of the rocks involved in the earthquake (in Pa)
is the area of the rupture along the geologic fault where the earthquake occurred (in m2), and
is the average displacement on
(in m).