Providing multidisciplinary scientific advice for coastal planning in Kitimat Arm, British Columbia

Abstract

A 6.3 m tsunami swept through Kitimat Arm, British Columbia in 1974. An even larger wave struck and damaged the Northlands Navigation dock at Kitimat and the Haisla First Nation docks at Kitamaat Village the following year. Further down the fjord, two large coastal block failures were observed on the fjord walls across from the Gitga'at village of Hartley Bay. Several large infrastructure projects have recently been proposed for the Kitimat Arm coastal areas. The Geological Survey of Canada has therefore embarked on a five-year project to understand the magnitude and frequency of submarine mass movements in this fjord system to provide information regarding the risks from these events and to propose mitigation measures that may reduce these risks. We provide here an overview and the main results to date of an ongoing multidisciplinary study, which includes palaeotsunami studies, geomorphological and sub-seabed mapping, subaerial landslide hazard assessment, tsunami modelling, in situ and laboratory geotechnical testing, and the real-time tracking of seismic activity and seafloor movement. Some of these activities are reported in greater detail elsewhere in this book. The results of this research are summarized as a list of conclusions and recommendations to the Government of Canada.

Advancing from subaqueous mass movement case studies to providing advice and mitigation

“…This monitoring would complement the multidisciplinary approaches described in Vanneste et al (2012). Indeed, a combination of multidisciplinary and real-time monitoring approaches is being used in Kitimat, BC, where the magnitudes, frequencies and triggers of tsunamigenic submarine landslides has been deduced over 4 years of expeditions, and real-time underwater instruments are now monitoring for rock movements, audible and seismic indications of earthquakes and landslides, and seismic seiches and tsunamis (Lintern et al 2019).…”