Angle gathers

Common-image gathers are closely related to the angle reflectivity, which can be used for AVA analysis or AVA inversion. Unfortunately, macro-velocity errors will cause amplitude aberrations in common-image gathers. Therefore, some traps in AVA analysis or inversion should be carefully avoided. However, residual depth or time differences are present in the common-image gathers if macro-velocity field has errors; these differences can be used for migration velocity analysis.

On the other hand, the amplitude-preserving common-image gathers may be generated from inverse imaging.