Page 548 - Acquisition and Processing of Marine Seismic Data

11.12 QC IN MIGRATION 539

FIG. 11.47 Poststack Kirchhoff time migration results of an input dataset with (A) 3.125 m, (B) 6.25 m, and (C) 12.5 m CDP
intervals. Finer trace intervals result in much higher resolution and sharper images after migration.

and a steeply dipping event. The Kirchhoff surface where the velocities are relatively low.
migration result with and without an antialias- One must suspect data aliasing if such system-
ing filter is given in Fig. 11.49B and C, respec- atic noise exists near the surface after migration.
tively. In the case where the spatial sampling Aliasing also occurs in prestack migration if
is not small enough, high-frequency compo- the data consists of steeply dipping events.
nents are spatially aliased, which causes artifacts Apart from Kirchhoff migration, which suffers
in the output image, especially close to the from operator aliasing, Zhang et al. (2003)