Abstract: A massively parallel computer arrangement and method for processing seismic data, comprising signal amplitude as received by a plurality of receivers each for a plurality of shots, to generate a profile of subterranean formations. Initially, the arrangement, iteratively for a plurality of subsets of the shot data referred to as "shot chunks," converts, the signal amplitude data into frequency component amplitude data identifying the amplitudes of the frequency components of the signal data. After that is done for all of the shot chunks, the arrangement iteratively processes the amplitude data for successive frequency chunks to generate a profile, during each iteration iteratively generating profile information for successive subterranean layers and processing the frequency component amplitude data to downward-migrate the receiver and shot data to facilitate generating profile information for the next layer.