Large submarine slope failures and associated Quaternary faults in Douglas Channel, British Columbia

Very large (>60 x 106 m3) submarine slope failures occur in Douglas Channel, British Columbia. Geophysical and core data suggest that these failures were episodically active between 13 ka and 11 ka radiocarbon years BP. Radiocarbon ages indicate thatregionally, near continuous sedimentation has been ongoing for approximately the last 10 000 a and that this deposition has not been interrupted by sedimentary units indicative of large-scale slope failures. The new data support an inferred bedrock sagging or sackung origin for the bedrock slidesthat occurred along bounding faults after support by buttressing glacial ice had been removed. Faulting, observed in seismic data affecting the Late Glacial section south of the slide area, may have contributed to slope instability along the southeastern shoreline of Douglas Channel. The observedfault may have been reactivated during glacial loading and unloading or may result from an existing regional, north-south-oriented, dextral-shear stress regime.