Magnetic Survey Off the West Coast of North America, 40° N. Latitude to 52° N. Latitude

Site Survey of Paul Revere Ridge West of Northern Vancouver Island

“…DSDP Site 177 is located at the north end of Paul Revere Ridge. Figure 3 shows that the pronounced magnetic anomalies (Raff and Mason, 1961;Couch, 1969) (Srivastava et al, 1971) and very fresh basalt dredged, from a valley near 5O°2θ'N latitude, 130°10'W longitude support this interpretation. Although high heat-flow values are observed in postulated spreading centers immediately west of Paul Revere Ridge, (Couch, 1970;Srivastava et al, 1971) approximately normal heat flow is observed in Winona Basin (Couch et al, 1970, unpublished).…”

“…Interpretation of the magnetic anomalies, although different by different investigators (Pavoni, 1966;Vine, 1966;Peter and Latimore, 1969;Atwater, 1970), indicates that the tectonism extends from the Pliocene to the Holocene. Seismic profiling (Couch, 1969;Tiffen et al, 1972;Bertrand, 1972;McManus et al, 1972) and earthquake studies (Tobin and Sykes, 1968;Wetmiller, 1971) Raff and Mason, 1961). Dehlinger et al, 1971, with …”

Seismicity and crustal structure at the Mendocino triple junction, Northern California

“…Raff and Mason [1961] first mapped and noticed strong curvatures in magnetic lineations to the east of the Gorda ridge. Addition-ally, Silver [1971] noticed their counterparts on the that these Iineations are tens of kilometers shorter than western half of the ridge.…”

The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers

“…While the Juan de Fuca Ridge is remarkably aseismic, the Gorda Ridge is very seismically active with microearthquake focal depths extending to the mantle (7 ± 2 km [Johnson and Lewis, 1984] or 15 ± 2 km depth [Solano and Bibee, 1985)). The earthquake density per 55 km of ridge length normal to the transform direction was 15-20 times greater along the Gorda Ridge than along the Juan de Fuca Ridge during the period 1961-1969[Environmental Science Services Administration, 1970. Recent monitoring of the northeast Pacific using the more sensitive military Sounds Surveillance System (SOSUS) hydrophone arrays has confirmed the relative seismic quiescence of the Juan de Fuca Ridge compared to the Gorda Ridge .…”