The Mendocino fracture zone is a fracture zone and transform boundary over 4000 km long, starting off the coast of Cape Mendocino in far northern California. It runs westward from a triple junction with the San Andreas Fault and the Cascadia subduction zone for about 300 km to the southern end of the Gorda Ridge. It continues on west of its junction with the Gorda Ridge, as an inactive remnant section which extends for about 4,000 km to approximately 35°N 175°W.