Seismic Wave Propagation
The subsurface of the earth comprises rock layers that have different physical properties and are in contact with one another (i.e., are stratified). The boundaries separating the individual layers are referred to as interfaces. Those interfaces may represent contacts between, for example, a sand layer and a shale layer (i.e., a sand-shale interface), or between a shale layer and a limestone layer (a shale-limestone interface), or they may be an interface between gas-filled and water-bearing layers of sandstone. It is helpful to understand the propagation of sound waves through such subsurface interfaces. A simple way to model the partitioning of energy at an interface is to consider a basic model of the subsurface, in which the interface is perfectly planar and separates two infinitely homogeneous, isotropic, elastic media. We refer to such an interface as an ideal reflector.