Studies of Seismogenesis and Plate Boundary Structure on Canada's West Coast

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Plate boundary faults endanger over 3 million people and societal infrastructure along Canada's west coast. The greatest seismic hazard arises from the Cascadia Subduction Megathrust that extends from northern California to northern Vancouver Island, approximately ~150 km west of the coastline. This plate boundary has experienced M=9+ earthquakes at intervals averaging ~550 years and is capable of generating tsunamis and ground shaking comparable to recent great earthquakes in Japan (2011) and Indonesia (2004). The second plate boundary of concern is the Queen Charlotte Fault that extends north of Vancouver Island along the coast of Haida Gwaii. In 1949 this fault generated Canada's largest historically recorded earthquake (M=8.1). On October 27 2012, a M=7.8 earthquake beneath Haida Gwaii spawned a small tsunami and highlighted the existence of an additional, major thrust fault dipping to the northeast beneath Moresby Island.