Book excerpt: This report presents the results of a study of the coupling of seismic energy to the SOFAR channel and the propagation of acoustic energy from source to receiver. The results of an investigation of T-phase amplitude level vs. earthquake magnitude are presented for events in the Pacific ocean. The poor correlation between these parameters suggests that the generation of detectable T-phases is dependent not only upon event magnitude and depth, source mechanism, and transmission loss from source to receiver, but also on details of the source bathymetry which govern the coupling of seismic to acoustic energy. Despite the complexities of the data, several features of T-phase data that are readily observable are: (1) T-phase energy for submarine earthquakes drops off rapidly at frequencies greater than 16 Hz, and (2) that the nature of the T-phase coda is strongly dependent on the geographic source area, thus T-phases from the same area tend to be very similar.