Recently collected multibeam bathymetry and hydroacoustic earthquake data are used to investigate the recent tectonics of the Explorer–Juan de Fuca Ridge systems, the boundaries between the Pacific and northern Juan de Fuca plates. The bathymetric and seismic evidence presented is consistent with a zone of shear extending well south of the Sovanco Fracture Zone to include the Heck and Heckle seamounts, and potentially as far south as the Springfield Seamounts and Cobb offset along the Juan de Fuca Ridge. This indicates that the triple junction between the Pacific–Juan de Fuca–North American plates may be reorganizing southward to establish at the Cobb offset.

Keywords: bathymetry, earthquakes, hydroacoustics, ridge, transform, Juan de Fuca