What is the seismic moment of an earthquake and what is it used for?

1 Answer
May 27, 2016

Answer:

Seismic moment is measure of the size of an earthquake and it is used in order to calculate moment magnitude.

Explanation:

Seismic moment is an important value for earthquake magnitude determination. Seismic moment , #M_0#, is related with the rigidity of the eartquake source region, #mu#, area of the fault plane, #A# and average displacement, #D#. Equation of #M_0# can be seen as below,

#M_0 = mu A D#

By using #M_0# moment magnitude, #M_w# can be calculated,

#M_w = 2/3 log(M_0) - 10.7#.

Determining #M_w# is important since, #M_w# cannot saturate unlike other magnitude scale. This property of #M_w# comes from the feature of #M_0#. Other magnitude types are depended with certain part of seismic records. Seismic records, however, can satured if the magnitude of the earthquake is bigger than a certain magnitude. Because of that #M_0# has a vital role on modern seismology.

The seismic moment can be also interpreted in terms of the strain energy released in earthquakes.