A method and program for processing a volume of data such as seismic data on a parallel computer system having a distributed memory system, a host node and a plurality of worker nodes. The output data volume is sliced into horizontal slices and one or more slices are assigned to each worker node. Each worker node performs Kirchoff 3D DMO operations on that portion of the input traces for processing the horizontal slice or slices assigned to that processing node, and passes the output slices to the host node. The host node then assembles the slices into the output data volume. Where there are M worker nodes and the number of slices exceeds M, every M.sup.th slice is assigned to a worker node in a round-robin fashion to balance the load among the worker nodes.