GEOACOUSTIC TOMOGRAPHY: RANGE DEPENDENT INVERSIONS ON A SINGLE SLICE

A hybrid inversion scheme is used for the inversion of bottom geoacoustic properties using synthetic data as well as broadband signals from explosive sources. This technique is shown to be effective for range dependent inversion on a single slice using synthetic and experimental data. The experimental data was acquired during the Shelf Break Primer Experiment. Time-frequency analysis was performed using wavelets. Group speeds obtained from the time-frequency scalograms were used as data for the inversion. The hybrid method consists of a Genetic Algorithm, which performs the global search, and a Levenberg-Marquardt method, which hastens the descent to the global minimum. Error estimates based on Hessians and a posteriori variances are also provided. Resolution is estimated using an a posteriori analysis.