Imaging Near Surface Scatterers by Scattered Surface Waves - Revamping an Inverse Scattering Code

We use an inverse scattering method for imaging the near surface scatterers by scattered surface waves. The method involves three dimensional elastodynamic wave propagation and scattering in a layered medium. The scattered wavefield is due to density contrast only, and is given as an integral representation by considering Born approximation. For efficient modeling and inversion, we converted our legacy computer code, developed for the method, into a newer programming language. Also, parallel programming techniques were introduced into the code to increase its efficiency. A simple parallelization structure was implemented, which resulted in a significant decrease in program runtime. We validated the code by comparing its modeling output with a finite-difference modeling of wave propagation program. We used half space models with scatterers that have positive and negative density contrasts in both programs and compared the results. Scattered wavefields obtained from the finite-difference modeling are used in our revamped code for imaging. Inversion results for both scatterer cases show that the location and density contrasts of the scatterers are reasonably well estimated.