Aliasing in prestack migration

John C. Bancroft

Aliasing is a common problem in seismic processing and is usually associated with steeply dipping events and receiver spacing. However, it also effects horizontal data, and even the simple processing step of normal moveout (NMO). It may appear as noise on a migrated section, or as a coherent non-existing event.

The amount of aliasing in data can be controlled with a number of algorithms such as Kirchhoff migration. Aliasing becomes a compromise between the frequency content of dipping events, the dip angle of the events, the trace spacing of the input data, and the (aliasing) noise content. The trace spacing is defined by the source and receiver intervals relating cost to the aliasing compromise.

This paper will review the basic principles behind aliasing, address the techniques used to eliminate or reduce aliasing, and describe the natural antialiasing effects of Equivalent Offset migration.