Geophysical Journal International Geophys. J. Int. (2015) 201, 372–376 doi: 10.1093/gji/ggv026 GJI Geodynamics and tectonics EXPRESS LETTER Numerical simulation of the December 4, 2007 landslide-generated tsunami in Chehalis Lake, Canada Jiajia Wang,1 Steven N. Ward2 and Lili Xiao1 1Faculty of Engineering, China University of Geosciences, Wuhan 430074, China. E-mail:
[email protected] 2Institute of Geophysics and Planetary Physics, University of California, Santa Cruz, CA 95060, USA Accepted 2015 January 13. Received 2015 January 11; in original form 2014 November 6 SUMMARY On December 4, 2007, a three million cubic metres landslide impacted Chehalis Lake, 80 km Downloaded from east of Vancouver, Canada. The failed mass rushed into the lake and parented a tsunami that ran up 38 m 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 ∼60 m s–1, and a slide mass stoppage with uniform repose angle on the lakebed. Tsunami http://gji.oxfordjournals.org/ 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. Key words: Numerical approximations and analysis; Tsunamis; Fracture and flow; North America. by guest on February 26, 2015 wide and 500–840 m a.s.l, bounds the primary rock failure with 1 REVIEW OF THE 2007 EVENT AND a volume of ∼2.2 M m3,anareaof∼54 000 m2 and an average OBSERVATIONAL DATA thickness of ∼40 m (Brideau et al.