Seismic waveform tomography with multicomponent data at a groundwater contamination site
This thesis develops an SH-wave version of frequency-domain, full waveform tomography, and applies it, together with traditional acoustic waveform tomography, to a multicomponent seismic data set acquired over a shallow contaminated aquifer at Hill Air Force Base, Utah. The study combines the high resolution provided by waveform tomography with inherent advantages of SH-wave imaging, such as reduced seismic velocity and independence of pore fluid content. Presented are synthetic tests of the method, its application to the field data, and interpretation of the resulting P- and S-wave velocity models.
Synthetic tests reveal fundamental differences between acoustic and SH waveform tomography, and demonstrate, together with the field data inversions, improved resolution for SH-wave imaging due to smaller velocities. High-resolution velocity models from inversion of the field data are interpreted in terms of lithology and water saturation, which are better constrained by the availability of both P- and S-wave velocity.