Migration Velocity Analysis (MVA) is one of the most important applications of ADCIGs, and the main focus of this paper. MVA from ADCIGs computed using wavefield-continuation migration is conceptually analogous to MVA from conventional offset-domain CIGs obtained by Kirchhoff migration. The ADCIGs are analyzed for departure from flatness, usually by applying some kind of Residual Moveout (RMO) analysis. The RMO analysis provides measurements of depth errors that are first transformed into traveltime perturbations and finally inverted into velocity perturbations by a ray-based tomographic inversion. This process is repeated several times in order to converge to a satisfactory result.
In this section we analyze the kinematic properties
of 3-D ADCIGs when the migration velocity
is not correct.
First, we qualitatively analyze the
sensitivity of the estimation of the angles 
to velocity errors.
Second, we develop a quantitative
relationship between depth errors
in ADCIGs and traveltime perturbations
caused by velocity errors.
Third, we present a 3-D RMO function
for measuring the depth errors in ADCIGs.
Finally, we compare the imaging-point shifts
predicted by our results
with the actual images produced
from a synthetic data set migrated with the wrong velocity.
to velocity errors