Palaeotsunamis along Canada’s Pacific coast

Abstract

To fully understand tsunami hazards along Canada’s Pacific coast we must consider all potential sources including local and region-wide earthquakes, volcanic activity, slope failure events and bolide impacts. Furthermore, as climate changes, future extreme meteorological conditions will exacerbate slope failures on steep and over-steepened slopes, and potentially augment the magnitude and frequency of earthquake-generated tsunamis. There have been numerous reviews of the geological records of palaeotsunamis along the Cascadia margin, but as yet there has been no attempt made to pull together all data related to palaeotsunamis along the Pacific coast of Canada. We summarise all geological data related to palaeotsunamis reported in the region, all relevant non-geological data, and other information concerning potential tsunamigenic sources. Evidence for between 10 and 22 palaeotsunamis (prior to European arrival) have been documented, with the Cascadia Subduction Zone Y event (AD1700) being the most widely recognised. Geological, archaeological and anthropological data all indicate a complex, multi-sourced, prehistory of seismic/tsunami activity that is poorly understood. A clustering of potential activity off the SE coast of Vancouver Island suggests that we should also attempt to better understand locally generated events along Canada’s Pacific coast.