Infrasound arrays in the Pacific and Indian oceans that are part of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty (CTBT) recorded distinct signatures associated with the 26 December 2004 Sumatra earthquake (M9, httpc//earthquake.usgs.gov/) and tsunami. Although the radiation of infrasound from large continental earthquakes is established Le Pichon et al., 2003>, the results presented in the present article indicate that islands undergoing significant surface displacements from submarine earthquakes can produce infrasound. Far more intriguing is the possibility that the initiation and propagation of a tsunami may produce low-frequency sound near the source as well as along coastlines and basins. Since distant sound effectively propagates at ˜300 m/s and tsunamis propagate at ˜200 m/s, precursory sound could potentially be used as a discriminant for tsunami genesis.