The earth model is arbitrary. We choose to have a single flat reflector and a single or a few point diffractors. The flat reflector gives a flat event. In the following figure, IZO image is on the left and DMO image is on the right. It shows much more strongly on the DMO image on the right.
Time slices through the hyperboloid are circles.
Frequency slices are Bull's Eyes due to the interference between the hyperboloid and the flat reflector. Here, DMO is on the left and IZO on the right. The acquisition footprint overwhelms the DMO image on the left so the Bull's eyes do not show in this figure. The Bull's eyes are visible on the IZO image on the right. Comparing different processing methods, NMO, DMO, and IZO, we see that for this geometry only IZO gives an image free of geometry footprint.