The 27 April 1975 Kitimat, British Columbia, submarine landslide tsunami: a comparison of modeling approaches

Abstract

We present numerical simulations of the April 27, 1975, landslide event in the northern extreme of Kitimat Arm, British Columbia. The event caused a tsunami with an estimated wave height of 8.2 m at Kitimat First Nations Settlement and 6.1 m at Clio Bay, at the northern and southern ends of Kitimat Arm, respectively. We use the nonhydrostatic model NHWAVE to perform a series of numerical experiments with different slide configurations and with two approaches to modeling the slide motion: a solid slide with motion controlled by a basal Coulomb friction and a depth-integrated numerical slide based on Newtonian viscous flow. Numerical tests show that both models are capable of reproducing observations of the event if an adequate representation of slide geometry is used. We further show that comparable results are obtained using estimates of either Coulomb friction angle or slide viscosity that are within reasonable ranges of values found in previous literature.