The Leech River Fault (red) across the southern tip of w:Vancouver Island and the Tofino, West Coast, Hurricane Ridge (portion), San Juan, Survey Mountain, Devils Mountain, and Southern Whidbey Island faults, and the projected extension of the Leech River Fault through Discovery Bay. These all dip to the northeast. Stippled area is Pacific Rim terrane. Also shown: Cape Flattery, San Juan Island, and the cities of Port Renfrew, Sooke, Port Angeles, Port Townsend, and Victoria.

The northeast extension of the San Juan fault may be an older feature, unrelated to the main part of the San Juan fault [Clowes et al., 1987, p. 35]. A recent study [Hayward et al, 2006, fig. 2] shows the Leech River Fault aligned with the SWIF, with multiple splays branching off towards Discovery Bay. Some early studies [Clowes et al., 1987] located the Tofino Fault (upper contact of the Crescent Terrane) on the coast, implying direct contact of Siletzia and Wrangellia north of SJF. The location shown here follows the interpretation of Hyndman et al., 1990; see also Dehler and Clowes, 1992.

This figure was derived from the following sources:

• “Geological interpretation of magnetic and gravity anomales in the Strait of Juan de Fuca, U.S.—Canada”, in Canadian Journal of Earth Science, volume 14, issue 2, 1977-02, DOI:10.1139/e77-024, pages 223-238.
• The Leech River Unit and Leech River Fault, Southern Vancouver Island, British Columbia, Univ. of Washington [masters thesis], 1979.
• Structure and Petrology of Pre-Tertiary Rocks Near Port Renfrew, Vancouver Island, British Columbia, Univ. of Washington [masters thesis], 1982.
• “LITHOPROBE — southern Vancouver Island: Cenozoic subduction complex imaged by deep seismic reflections”, in Canadian Journal of Environmental Science^[1], volume 24, issue 1, 1987-01, archived from the original on 2012-03-27, pages 31-51.
• “Crustal structure beneath the Strait of Juan de Fuca and southern Vancouver Island from seismic and gravity analyses”, in Journal of Geophysical Research^[2], volume 108, issue B10, 2003-10, DOI:10.1029/2002JB001823.
• “The northern Cascadia subduction zone at Vancouver Island – Seismic structure and tectonic history”, in Canadian Journal of Earth Science, volume 27, issue 3, 1990-03, DOI:10.1139/e90-030, pages 313-329.
• “Geology of a transpressional orogen developed during ridge-trench interaction along the North Pacific margin: Magmatic and tectonic history of the Leech River Complex, Vancouver Island, British Columbia: Evidence for ridge-trench intersection and accretion of the Crescent Terrane”, in Geological Society of America^[3], volume Special Paper 371, 2003, pages 327-353.
• “Structural variation along the Devil’s Mountain fault zone, northwestern Washington”, in Canadian Journal of Earth Science^[4], volume 43, issue 4, 2006, DOI:10.1139/E06-002, archived from the original on 2012-03-05, pages 433-466.

See also:

• “Integrated geophysical modelling of terranes and other structures along the western Canadian margin”, in Canadian Journal of Earth Science, volume 28, issue 7, 1992-07, DOI:10.1139/e92-119, pages 1492-1508.
• “Neotectonic mapping of eastern Juan de Fuca Strait, Cascadia Forearc Region: initial results”, in Geological Survey of Canada^[5], volume Open File 3868, 2001, DOI:10.4095/212058.