f The non-uniqueness of migration velocities

Typical 2D prestack seismic reflection data is not sufficient for resolving a laterally varying interval velocity field for pre-stack depth migration. Different subsurface models can produce data that is identical or identical enough that they cannot be distinguished. This ambiguity in the velocity field creates a corresponding ambiguity in the depth and structure of the reflectors. As a result, in areas of lateral velocity variations, we cannot rely on seismic data alone to resolve structure. The common sense and geologic knowledge of the interpreter must be incorporated info the problem with the use of inversion constraints.