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TitleA study of the tsunami effects of two landslides in the St. Lawrence Estuary
AuthorPoncet, R; Campbell, CORCID logo; Dias, F; Locat, J; Mosher, DORCID logo
SourceSubmarine mass movements and rheir consequences; by Mosher, DORCID logo (ed.); Advances in Natural and Technological Hazards Research vol. 28, 2010 p. 755-764, 61
Alt SeriesEarth Sciences Sector, Contribution Series 20090102
PublisherSpringer Netherlands
MeetingThe 4th International Symposium on Submarine Mass Movements and Their Consequences; Austin, TX; US; November 8-11, 2009
Mediapaper; on-line; digital
File formatpdf
ProvinceEastern offshore region
AreaSt. Lawrence Estuary; Matane; St-Siméon
Lat/Long WENS -70.0000 -67.0000 49.2500 47.7500
Subjectsmarine geology; geophysics; tsunami; landslides; landslide deposits; submarine features; submarine transport; glacial deposits; glaciomarine deposits; postglacial deposits; geophysical surveys; bathymetry; seabottom topography; seafloor topography
Illustrationslocation maps; graphs; profiles
ProgramGeoscience for Oceans Management
AbstractThe Lower St. Lawrence Estuary (LSLE) is a 230 km long by 50 km wide trough with a broad, flat floor with maximum water depths of 400 m and "shelves" that sit in water depths of < 60 m. It is partly filled with thick glaciomarine and post-glacial sediments and lies within close proximity to the Charlevoix Seismic Zone, the most seismically active region of eastern Canada. The purpose of this paper is to present the modelled tsunami effects of two submarine landslides from the LSLE. A regional seafloor mapping project revealed several submarine landslides on the slopes and channel floor of the LSLE. The tsunamigenic effects of two instability features in the area were investigated. The features chosen were: (1) a blocky submarine landslide that covers an area of ~3 km2, a run-out distance of 1.2 km and maximum slab thickness of 20 m; and (2) a lateral spread feature with a 4 km long headwall escarpment and a maximum slab thickness of 10.5 m, which may be a candidate for a future landslide. Using a numerical wave tank, the nonlinear shallow water equations were solved for motions induced by the submarine instability features. The equations are solved numerically by the finite volume method, and the code is able to model accurately tsunami runup and drawdown.

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