Numerical Simulation of the December 4, 2007 Landslide-Generated Tsunami in Chehalis Lake, Canada

adam ibrahim indrawijaya;

On December 4, 2007, a three million cubic metres landslide impacted Chehalis Lake, 80 km east ofVancouver, Canada. The failed mass rushed into the lake and parented a tsunami that ran up 38m on the opposite shore, destroyed trees, roads and campsite facilities. Armed with field
surveys and multihigh-tech observations from SONAR, LiDAR and orthophotographs, we apply the newly developed ‘Tsunami Squares’ method to simulate the Chehalis Lake landslide and its generated tsunami. The landslide simulation shows a progressive failure, flow speeds up to∼60ms–1, and a slide mass stoppage with uniformrepose angle on the lakebed. Tsunami products suggest that landslide velocity and spatial scale influence the initial wave size, while wave energy decay and inundation heights are affected by a combination of distance to the landslide, bathymetry and shoreline orientation relative to the wave direction.