A Tectonic Grinding Machine
Off the coast of British Columbia's Haida Gwaii archipelago lies a colossal fracture in the Earth's crust: the Queen Charlotte Fault. This 900-kilometer-long system is the Canadian counterpart to California's San Andreas Fault, the active boundary where the Pacific Plate grinds north-northwest past the North American Plate. The motion is relentless and rapid. The plates slide past each other at a rate of about 50 to 57 millimeters per year, making it one of the fastest-moving continent-ocean strike-slip faults on the planet.
This structure is a right-lateral strike-slip fault, meaning if you could stand on the North American Plate and look west, the Pacific Plate would be moving to your right. The fault extends from a complex junction with the Cascadia subduction zone off northern Vancouver Island, northward along the coast until it becomes the Fairweather Fault in Alaska. Together, they form the massive Queen Charlotte-Fairweather Fault system. While it is primarily a transform boundary, the plate motion is not perfectly parallel. A component of convergence—the plates pushing into each other—exists, particularly in the southern section near Haida Gwaii. This "transpressional" force causes crustal thickening and has recently been confirmed to be creating a new zone of subduction, where the Pacific Plate is beginning to dive under North America.