Figure depicts the two-layer model and the 3-D-recording geometry. An equivalent homogeneous block of finely layered shale is situated on top of a homogeneous fractured chalk layer. We employ a P-source and three-component receivers about 1 km above the interface. A surface seismic survey is modeled with a large aperture. The chalk fracturing is calculated using Hudson's theory combined with Schoenberg & Muir group theory. The actual stiffness coefficients can be found in Appendix A. The unfractured elastic constants were derived from constants published by Wright 1987. Using a macro model description of the fractured chalk and finely layered shale, we can employ a FD modeling method which works efficiently on a large - the actual surface seismic - measurement scale.