Definition of Seismic Moment at a Discontinuity Interface

When considering a seismic source operating along a discontinuity interface, seismic moment has to be redefined considering the jump of rigidity. The traditional definition of seismic moment may lead to underestimation of the slip or rupture length of an earthquake. Redefined seismic moment can be represented as M0 = (mu) (delta)uA, in which (mu), the effective rigidity, can be represented by the average rigidity (mu)and the difference of rigidity across the interface (delta)(mu) via (mu)= (mu){1-((delta)(mu)/2(mu))^2}