Reduced memory implementation of a local elastic finite-difference solver

The recovery of elastic properties from seismic data often requires the iterative use of seismic modeling. Finite-difference (FD) simulation is a common component in seismic modeling, and it is usually the most computationally expensive step in methodologies such as inversion or reverse time migration. Local solvers attempt to reduce the cost of FD simulations by reducing the computational domain to small areas, updating the model within these areas without recomputing throughout the full domain. We have implemented a local elastic solver that allows us to propagate the elastic wavefield within a subvolume after local alterations of the model. We determine how the scattered wavefield due to the alterations can be extrapolated from the local domain to surface receivers. We extend existing works by using the method of multiple point sources to recompute the wavefield within the local domain. This method is memory efficient because it only requires the global wavefield to be recorded along the local domain boundary. By injecting these recordings as point sources, the global wavefield is emulated within the local domain. Thus, the method requires no modifications of standard FD solvers, merely the ability to record and inject data. We evaluate the capability of the local elastic solver to reconstruct the wavefield in a subvolume of the elastic SEAM elastic model.