Page 521 - Acquisition and Processing of Marine Seismic Data

512 11. SEISMIC MIGRATION

FIG. 11.21 Effect of depth step size on the output of finite-difference time migration. 1 ms is the sampling rate of the stack
section. Higher depth step sizes simply cause undermigration.

the frowns are not as intensive as those for 11.4 FREQUENCY-WAVENUMBER
Kirchhoff migration (Fig. 11.22). The inclined (f-k) MIGRATION
events are not relocated to their true lateral
positions, and the diffractions cannot be col- At the end of the 1970s, Stolt (1978) suggested
lapsed for slower velocities. Yılmaz (2001) that migration can be implemented using the
indicates that higher velocities cause excessive Fourier transform, and then Gazdag (1978) pro-
dispersion since they lead to overmigration. posed the migration algorithm using the phase