Nonlinear Scattering-based Imaging in Elastic Media

Enabling nonlinear, elastic imaging using multicomponent seismic data is a key step in moving towards 'true-amplitude' imaging of the subsurface. Nonlinearity here refers both to the fact that even singlescattering interactions are in reality nonlinear (often ignored in Born-scattering migration methods), and to the nonlinearity introduced by the multiple interactions of reverberating waves with the structure to be imaged. Multiples are usually considered as noise in traditional linear imaging methods, and the nonlinearities of individual scattering events are simply ignored. We derive two new, nonlinear elastic imaging conditions based on reciprocity theory that are suitable for reverse-time imaging of land and marine ocean-bottom data. A synthetic example shows that these outperform the best existing elastic imaging conditions, highlighting the importance of handling interactions between multiply scattered and converted waves properly. Focusing such energy in the new methods better illuminates the target and reduces imaging artifacts.