An important aspect of seismic exploration and research are programs for creating synthetic data. Such programs find their use, both in the practical problem of modeling real data, as well as in the testing of new processing programs. A processing program that will not work on idealized model data will likely not work on real seismic data.
Another important aspect of modeling programs is the fact that many seismic processing algorithms (such as migration) may be viewed as inverse processes. The first step in such an inverse problem may be to create a method to solve the forward problem, and then formulate the solution to the inverse problem as a ``backpropagation'' of the recorded data to its position in the subsurface.
There are two parts to the seismic modeling task. The first part is the construction of background wavespeed profiles, which may consist of uniformly sampled arrays of floating point numbers. The second part is the construction of the synthetic wave information which propagates in that wavespeed profile.
Because of the intimate relationship between seismic modeling and seismic processing, background wavespeed profiles created for modelling tasks, may also be useful for processing tasks.
Of course, if some simple assumptions are made, it may be possible for background wavespeed information to be built into the modeling program.