PARAGLACIAL SEDIMENTATION IN VANCOUVER’S NEIGHBOURING FIORD, HOWE SOUND, AND ITS IMPLICATIONS FOR EVALUATING FIORD TSUNAMI HAZARD

Howe Sound (HS) is the magnificent fiord next door to Vancouver. Fiords come with a constellation of related natural hazards. These are of increasing concern as fiords along the British Columbia coast become more populated and are proposed locations for Alberta tar sands bitumen and liquefied natural gas export terminals. Swath multibeam bathymetry (SMB) and piston coring have yielded new insights into natural hazards in and around HS: in particular evaluation of fiord tsunami potential. No evidence has been found to suggest that large, rapidly moving landslides entered lower HS during the latter half of the Holocene. This conclusion is based on interpretation of the stratigraphy of piston cores. Data from these support the view that the paraglacial effect strongly influenced the Holocene sedimentary history of HS. The paraglacial effect is documented widely in terrestrial Holocene landforms within the formerly glaciated Cordillera and river systems that flow from it. On this basis, deposits of landslides large enough to cause large displacement waves during the last ~5000 years should be visible to SMB. None exist on the sea floor of HS.