Full-waveform inversion of cross-hole GPR data measured at the boise gravel aquifer

Cross-hole radar tomography is a useful tool for mapping shallow subsurface dielectric permittivity (ε) and electrical conductivity (σ) parameters. Conventional ray-based tomography suffers from some shortcomings: it provides relatively low resolution images and it cannot supply reliable information on certain types of low velocity structure. Higher resolution images can be provided by full-waveform inversion that uses significantly more information of the data. Since the first application of full-waveform inversion on experimental GPR data, the algorithm has been significantly improved. An overview is given of all developments by applying different versions of the full-waveform inversion to the experimental data set acquired at the Boise Hydrogeophysics Research Site in Idaho. Almost all improvements resulted in a reducing final misfit between the measured and synthetic data and a reducing gradient at the final iteration.