The crucial analysis step in seismic processing is to establish an optimal velocity model. The quality of the velocity model has a major influence on the quality of the final processing result. The quality of the velocity model can be measured by how well the velocities NMO-correct the common reflection-point gathers (CRP). However, after transformation of the CRP-gathers to zero offset, it is impossible to validate the quality of the velocity model without invoking the prestack CRP-gathers. It is prohibitive to pass an undecimated prestack seismic data volume to the interpretation stage. As a result of this, the interpreter has no means to assess the quality of the velocity model. This might lead to pitfalls and misinterpretations. We propose a new compact quality metric for the velocity model that allows the interpreter to relate all seismic events in the zero-offset cube to quality measures of the NMOcorrection that resulted in these seismic events. The primitives of the quality measure are Residual Wavefront Normals (RWN) computed for every wavefront in the prestack gathers.

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