The Queen Charlotte Fault is a major right-lateral transform boundary running roughly 900 kilometres along the seafloor off the coast of British Columbia and southeastern Alaska, just west of Haida Gwaii. It marks the boundary where the Pacific Plate slides northwest past the North American Plate, making it Canada's closest analogue to California's San Andreas Fault.
Because it lies almost entirely offshore, the fault produces powerful earthquakes with relatively little direct shaking of populated land, though it can generate tsunamis and underwater landslides. It transitions northward into the Fairweather Fault and southward toward the Cascadia subduction zone, sitting at a complex junction of the Pacific plate margin.
The fault ruptured in Canada's largest recorded earthquake, the 1949 magnitude 8.1 event off Haida Gwaii. More recently the 2012 Haida Gwaii earthquake (magnitude 7.8) showed the fault can also host thrust motion where the Pacific Plate partly underthrusts North America, generating a small tsunami along the coast.