Tectonics of the Georgia Basin, northwest Washington State, USA, and southwest British Columbia, Canada

Abstract

GPS strain and recent neotectonic studies in northwest Washington and southwest British Columbia indicate long term north-south shortening of the Cascadia forearc extends north of recognized active faults. This study reviews seismic reflection profiles from the SHIPS 1998 and 2002 experiments in conjunction with industry data to identify active geologic structures capable of accommodating this unaccounted strain. Here a new active northeast striking thrust system in southern Strait of Georgia is identified, the fault ruptured during the 1997 earthquake near Gabriola Island and Vancouver B.C. is imaged, and the first subsurface images of the Sandy Point Fault are presented.