FY 1992

Ridge event detection: T-phase signals from the Juan de Fuca spreading center

Hammond, S.R., and D.A. Walker

Mar. Geophys. Res., 13(4), doi: 10.1007/BF00366282, 331–348 (1991)

An analysis of T-phase source locations determined in the mid-1960s for an area of the northeast Pacific Ocean encompassing the Juan de Fuca spreading center reveals that most of the source locations are associated with regions where seamount chains intersect the spreading center and with edifices both along and near the spreading center. The T-phase source locations also tend to cluster on, or near, areas of the most concentrated and vigorous hydrothermal venting along the Juan de Fuca Ridge. Of the 58 T- phase source locations determined for a period from October 1964 through December 1966, only one was found to be associated with an earthquake detected by the National Geophysical Data Center/National Earthquake Information Service because of the characteristic small magnitude of spreading-center seismic events. Monitoring T-phase activity originating along the 80,000 km-long global seafloor spreading-center system offers a practical and unique opportunity to better understand the dynamics and oceanic effects of episodic spreading-center tectonic, volcanic, and hydrothermal processes.