(9) |

We use this definition to define a MZO operator not only for a constant velocity medium, but for any variable velocity medium. The impulse response of the generalized can be defined by a two step process:

- 1.
**Full prestack migration to a depth model**. The prestack depth model is the position in space of all points that can generate a given impulse in a constant-offset section. For a constant velocity medium this is equivalent to constructing the migration ellipse for a constant-offset section. For a variable velocity medium, the loci of points with equal travel-time from source to receiver form a curve resembling an ellipse or a superposition of several ellipses.- 2.
**Zero-offset modeling**. Given the depth model, raytrace back at 90 degrees from the reflector, to model the zero-offset data. The intersection of the ray with the surface will give the x-coordinate of the MZO operator, while the travel-time along the raypath will provide the zero-offset time-coordinate.

Using this definition we can find another path to derive analytically the DMO operator in constant velocity media.

11/18/1997