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TitleEvidence of paleoseismicity within the West Quebec Seismic Zone, eastern Canada, from the age and morphology of sensitive clay landslides
AuthorBrooks, G R
SourceAbstracts Volume, 6th international INQUA meeting on paleoseismology, active tectonics and archaeoseismology; 2015 p. 59-62
Alt SeriesEarth Sciences Sector, Contribution Series 20140369
Meeting6th INQUA International Workshop on Active Tectonics Paleoseismology and Archaeoseismology; Pescina; IT; April 19-24, 2015
File formatpdf
ProvinceOntario; Quebec
NTS31G/05; 31G/12; 31F/08; 31F/09
AreaOttawa; Gatineau; Ottawa River; Quyon; Gatineau River; Ottawa Valley
Lat/Long WENS-76.5000 -75.5000 45.7500 45.2500
Subjectsgeophysics; surficial geology/geomorphology; landslides; landslide deposits; slope failures; slope stability; slope stability analyses; slope deposits; clays; sensitive clays; seismic zones; seismic interpretations; Champlain Sea
Illustrationslocation maps; digital elevation models
ProgramWestern Canada Geohazards Project, Public Safety Geoscience
AbstractTwo groups of 13 and 12 sensitive clay landslides aged between 5000-5400 and 980-1060 cal BP, respectively, are present within a dataset of 50 dated landslides from the Ottawa Valley, eastern Canada. The landslides within these groups include side-scarp failures, failures involving the simultaneous collapse of deposits along both sides of a stream course, and failures located along the sides of a confined valley. Both landslide groups are interpreted to have been triggered by paleoearthquakes, based on the setting and morphology of the landslides, and an assessment of other possible mechanisms. The estimated magnitudes are Mw 6.4 (5000-5400 cal BP event) and Mw 6.1 (980-1060 cal BP event). Side-scarp landslides with intact debris fields are the most promising morphology to date for identifying groups of commonly-aged sensitive clay landslides.
Summary(Plain Language Summary, not published)
This paper summarizes the results of research into the age of large, prehistoric landslides in the Ottawa Valley, southeastern Ontario-southwestern Quebec. The results indicate that there are two groups of landslides with similar age ranges in the area. The best explanation is that the landslides in each groups were triggered by an ancient earthquake. The implications of these results are that earthquakes strong enough to trigger multiple, large landslides have occurred in the past and can be expected to occur in the future. Such an earthquake in the future can be expected to impact residents and critical infrastructure in the area.