In the Bismarck Volcanic Arc in Papua New Guinea, six fields of sediment waves were imaged with sonar. Sediment structures observed in seismic data and swath bathymetry are not unique and can result from predominantly continuous (bottom) currents, or episodic (turbidity) currents, or from deformation of sediment. Two of these wave fields overlap and appear to be of turbidity-current origin and modified by bottom currents, with one field unconformably overlying the other field. A field off the coast of Dakataua caldera displays an arcuate morphology, and a series of enclosed depressions within the field suggests creation by extensional deformation of...