Modern Imaging Using Seismic Reflection Data*

Imaging using seismic reflection data has undergone tremendous advances over the past few years. The advances have been fostered in part by the availability of faster computers that have made more reliable algorithms for migration imaging feasible. The conventional approach to migration imaging, ray-based Kirchhoff migration, has been improved by the use of multiple-valued traveltime tables, ray amplitudes, and ray phases that can be calculated from various ray-tracing implementations. Wave-equation imaging, based on implementations of solutions of the wave equation, one-way wave equation, and approximations to the Lippmann-Schwinger equation, has become tractable. Wave-equation methods take account of wave phenomena such as focusing, defocusing, and diffraction that are important in many geological environments where imaging is used for petroleum exploration. There have also been applications of various types of migration imaging in basic studies of Earth structure. Such studies have been made to investigate deep Earth structure and large-scale lithospheric structure using waveforms from teleseisms as sources.