Click for a Live Broadcast.
The Queen Charlotte Fault (QCF) is a dextral transform system that accommodates offset between the Pacific and North America plates in southeastern Alaska and western Canada. The seismically-active margin has recently ruptured in two large earthquake events, including a M7.7 thrust event near Haida Gwaii, Canada. Convergence along the QCF is highest south of 53.2°N due to a restraining bend in the fault, near where the Haida Gwaii thrust event occurred. The Haida Gwaii event is thought to have been caused by incipient underthrusting of the Pacific Plate related to the oblique convergence along the QCF in that region; however, the fault structure near the earthquake is poorly understood and the interface that slipped to cause the earthquake has yet to be explicitly imaged. Through updated seismic reflection processing, fault mapping, and seismic interpretation, we are able to better image and map the QCF along-strike and observe that strain manifestation could be related to fault geometry. We also observe downwarping of oceanic basement crust north of the Haida Gwaii event and suggest that this crust was once located in a more convergent regime, translated north along the QCF to its current position with its flexure "preserved" by sedimentary loading.