Reverse time migration with source wavefield reconstruction strategy

The reverse time migration (RTM) imaging condition requires that the source and receiver wavefields must be correlated at the same time. The source wavefield can be fully reconstructed backward in time if proper initial conditions and boundary values are chosen. In this paper, we present a method that can approximately reconstruct the source wavefield backward in time. At the price of losing spatial accuracy near the boundaries, the total amount of data storage can be significantly reduced. We compare two strategies for source wavefield reconstruction with both the constant-density acoustic wave equation and the pseudo-acoustic wave equation in transversely isotropic media. We also give a theoretical comparison of data storage and computation cost between the backpropagation strategies and the optimal checkpointing scheme. Numerical experiments show that the approximate source wavefield reconstruction scheme is feasible for RTM in terms of data storage and computation cost