This is a 2D dip line from a 2.5D model calculated using the 3D acoustic wave equation. For more information about the model, see Etgen and Regone (1998).
Also see the directory "SEG1998", which contains the above abstract and the talk slides that went with it.
This model was created by John Etgen and Carl Regone on the Amoco CM-5 in Tulsa. I got permission from Amoco just before the merger to publically release this data, which is a 2D dip line subset of the full synthetic 3D dataset. This dataset was meant to be a severe test of 2.5D Kirchhoff migration (the model is invariant in the Y direction). Carl Regone constructed the model and he is a big proponent of wavefield methods, so wanted something that would show up the limitations of Kirchhoff!