POSTSTACK MIGRATION OF P-SV SEISMIC DATA

The exploding-reflector model is only satisfied for zero-offset P-SV data when V(P)/V(S) is depth-invariant. P-SV diffractions in a vertically-inhomogeneous medium are approximately hyperbolic, and an expression for their migration velocity is derived. The resulting migration velocities are 6-11 percent less than the corresponding P-SV rms velocities. Migration of DMO-corrected synthetic P-SV stacked data, using a conventional phase-shift algorithm and the derived migration velocities, is found to adequately collapse diffractions, whereas migration using the rms velocity function gives significant overmigration.