DOIAbstract
Seismic waves travelling through the crust generate trains of scattered waves called the seismic coda. Coda motion u ( t) excited by a source pulse a(t) and recorded at times t> =2t0 by a sensor located at traveltime to from the source can be written as the convolution of a( [ ) with the gradient c ' ( r) = d,c(r) of spatial velocity fluctua-tions c ( r) encountered by the wave front at r = tco/2: u ( t) = 4nuI,(t,,/t)(c'(tc,,/2)) * a(t), where toft accounts for source wavelet spherical divergence, c,) is the mean seismic velocity of the medium, and ( ) denotes the scattering amplitude c ' ( r) averaged over the 47r solid angle of the wave front. I t follows that the coda frequency spectrum u ( f) is proportional ...
Add to ORKG