RTM (Reverse Time Migration) is a shot domain migration. Tsunami's RTM implements wave propagation calculations in a highly parallel environment for efficient propagation of the waves through subsurface media. By storing every source wave time step it solves the problem of reverse order access to the source time steps for correlation with those of the receivers.
Additionally, RTM 's program design addresses the challenges of managing jobs on large, heterogeneous clusters and minimizing the memory and disk storage requirements on compute nodes.