The Importance of Low Frequency and Large Offset in Waveform Inversion

Proper reconstruction of the velocity field implies the recovery of a continuous range of wavenumbers from the low to the high end of the spatial spectrum. While the very low-wavenumber components of the model can be recovered by reflection tomography, waveform inversion has the potential to recover both intermediate and high wavenumber components of the model by using the full range of offsets and frequencies in the seismic data. However, this process is inherently difficult due to the non-linearity of the inverse problem. To mitigate this non-linearity, it is important to provide an appropriate starting velocity model, and seismic data with sufficient low frequencies and wide-angle wave propagation.