地震矩 是地震学家用来表示地震所释放出之能量的数量，定义为:

其中: 为断层物质之刚性系数 (rigidity 或 shear modulus)，一般为 30x10 帕斯卡。 为断层之平均滑动量 (位移)。 为断层面积。

地震矩通常根据可获取之数据而估算。现代地震可使用地震仪的地震记录，古代地震则依靠地质学研究来推测断层之面积和滑动量。

地震矩规模是从地震矩演算而来的地震规模标度，现在常用来比较大型地震的强度。

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 , where

thus has dimensions of energy, measured in Joules or Newton meters.

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.