The Leech River Fault crosses the southern tip of Vancouver Island in British Columbia, Canada, running close to the city of Victoria and the surrounding capital region. It is a crustal fault with oblique, largely strike-slip motion, lying above the Cascadia subduction zone where the Juan de Fuca Plate dives beneath North America.
As a shallow fault within the overriding plate, it can rupture independently of the great offshore megathrust and pose a distinct hazard to a densely populated area. Its trace marks an ancient geological boundary that has been reactivated by present-day tectonic stress.
No large historical earthquake has been firmly assigned to the Leech River Fault, but paleoseismic studies reveal ruptures capable of magnitude ~6.5 to 7 in the past several thousand years. Its proximity to Victoria makes it an important focus of Canadian seismic hazard assessment.