Elastic reverse-time migration with an excitation amplitude imaging condition

The conventional cross-correlation imaging condition for elastic reverse-time migration (ERTM) produces significant artifacts. We develop an excitation amplitude imaging condition for ERTM to remove migration artifacts. During the forward propagation of the source wavefield, we store the maximum amplitude of the wavefield and the corresponding excitation time for each imaging point, and apply the cross-correlation imaging condition only at the excitation time and when the amplitude of the receiver wavefield at this excitation time satisfies a certain criterion. We demonstrate using synthetic multicomponent seismic data that our excitation amplitude imaging condition effectively removes migration artifacts for both PP and PS images. Our new imaging condition also significantly improves the computational efficiency and reduces the computer-memory requirement for ERTM.