The study of improved methods for calculating waveforms of elastic waves in three-dimensional media was extended to include poro-elastic media where there is attenuation of waves due to both intrinsic attenuation and scattering. Such media are commonly encountered in the shallow parts of the earth where the material occupying the pores can vary with both spatial position and time. It was found that this new formulation significantly improved the ability of the method to model realistic wave propagation effects. By extracting information on travel time and frequency dependent amplitude from seismograms through an inverse problem that involves complete simulations of the forward problem, it is now possible to make inferences about a number of material properties in heterogeneous media. These properties include velocity, intrinsic attenuation, porosity, and permeability.