Geometrical analysis of imaging

The notion of K-equivalence allows us to use a very simple approach to analysis of geometrical distortions on migrated sections that originated from a difference between the real medium and the model used at wave-field continuation. This difference may be caused not only by wrong velocities but also to use another Eiconal equation (when, for example, instead of anisotropic medium one uses the model of an isotropic one). The procedure of analysis is very simple:

• First step: solution of direct kinematical problem in the correct model; calculation of $\tau_0({\bf r}_0)$
• Second step: the reverse Eiconal's continuation
• Third step: imaging in a new model

We shall illustrate this procedure using a very simple example of a routine processing when one performs the time migration with wrong velocity and time-to-depth migration with correct velocity.