First step: The time *t _{0}* in a true model is the same as in the
example:

Second step: If we apply 15-degree algorithm with the continuation velocity , then discontinuities propagate in accordance to the Eiconal equation

(see equation (98) from Chapter 8 at ).The solution of this equation which satisfies boundary condition is:

Third step: From the condition we find location of the reflector image

when The factor so the depth distortion is very small for subhorizontal reflectors.1/13/1998