The purpose of this paper is to report the observation of anomalously long wavetrains of high-frequency seismic energy (0.3–1 Hz) following shallow events at a number of epicenters in the South-central Pacific basin, and to model their propagation and generation as due to efficient coupling of the oceanic water column with the solid Earth through a well-developed transitional layer of sediments. The following paragraphs are a short summary of the seismic features of the area, and provide a framework for our study.