Ignoring density in waveform inversion

Conclusion

As with travel-time based velocity analysis methods, the primary purpose for waveform inversion is to find a velocity model for imaging. However, waveform inversion needs to match data phase and amplitude, not just travel-times, and the examples in this report show that inverting for just velocity can be dangerous when density variations are significant. A possible solution is the joint inversion of density and velocity as proposed by Tarantola (1984). Further research is needed to determine whether seismic data typically contain the information necessary to constrain both fields.