Preliminary tsunami hazard assessment in British Columbia, Canada

Abstract:

Ocean Networks Canada (ONC), a not-for-profit initiative by the University of Victoria that operates several cabled ocean observatories, is developing a new generation of ocean observing systems (referred to as Smart Ocean Systems™), involving advanced undersea observation technologies, data networks and analytics. The ONC Tsunami project is a Smart Ocean Systems™ project that addresses the need for a near-field tsunami detection system for the coastal areas of British Columbia. Recent studies indicate that there is a 40-80% probability over the next 50 for a significant tsunami impacting the British Columbia (BC) coast with runups higher than 1.5 m. The NEPTUNE cabled ocean observatory, operated by ONC off of the west coast of British Columbia, could be used to detect near-field tsunami events with existing instrumentation, including seismometers and bottom pressure recorders. As part of this project, new tsunami simulations are underway for the BC coast. Tsunami propagation is being simulated with the FUNWAVE-TVD model, for a suite of new source models representing Cascadia megathrust rupture scenarios. Simulations are performed by one-way coupling in a series of nested model grids (from the source to the BC coast), whose bathymetry was developed based on digital elevation maps (DEMs) of the area, to estimate both tsunami arrival time and coastal runup/inundation for different locations. Besides inundation, maps of additional parameters such as maximum current are being developed, that will aid in tsunami hazard assessment and risk mitigation, as well as developing evacuation plans. We will present initial results of this work for the Port Alberni inlet, in particular Ucluelet, based on new source models developed using the best available data. We will also present a model validation using measurements of the 2011 transpacific Tohoku-oki tsunami recorded in coastal BC by several instruments from various US and Canadian agencies.