In exploration seismology, a process which collapses diffractions and moves reflections to their proper location in the seismic image. See Sheriff and Geldart (1995). seismic moment The magnitude of the component couple of the double couple that is the point force system equivalent to a fault slip in an isotropic elastic body. It is equal to rigidity times the fault slip integrated over the fault plane. It can be estimated from the farfield seismic spectrum or waveform fitting at wave lengths much longer than the source size. It can also be estimated from the near-field seismic, geologic and geodetic data, and the consistency among various observations. This was first demonstrated for the Niigata, Japan, earthquake of 1964, supporting quantitatively the validity of the fault origin of an earthquake. Also called "scalar seismic moment" to distinguish it from moment tensor. See slip moment and geodetic moment. See section 3.5 of Chapter 3 and exercises 3.4 and 3.5 in this Manual, Aki and Richards (2002 or 2009, p. 48-49), and section 2 in Ben-Zion (2003)