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TitlePaleoseismicity derived from piston-coring methods, Explorer and Juan de Fuca plate systems, British Columbia
AuthorRiedel, M; Conway, K W
SourceGeological Survey of Canada, Current Research (Online) 2015-10, 2015, 15 pages, (Open Access)
PublisherNatural Resources Canada
Mediadigital; on-line
File formatpdf
ProvinceWestern offshore region
Lat/Long WENS-128.0000 -126.5000 49.5000 48.5000
Subjectsgeophysics; fossil fuels; geophysical surveys; seismographs; seismological network; seismology; seismic waves; gas; acoustic surveys; acoustic surveys, marine; hydrate; permafrost; freezing ground; ground ice; bathymetry; continental shelf; continental slope; slope deposits; Juan de Fuca Plate; Explorer Plate
Illustrationslocation maps; tables; profiles
ProgramWestern Canada Geohazards Project, Public Safety Geoscience
Released2015 12 22
AbstractCoring of marine sediments has revealed deposits related to slope instability induced by seismicity on the western margin of Canada. Debris flows and turbidite sequences related to megathrust earthquakes have been recovered in six piston cores on the Juan de Fuca and Explorer tectonic plates, allowing comparison of the response of each plate to shaking during great earthquakes. Analyses of the recovered cores show that turbidite sequences associated with a megathrust quake occur on the Juan de Fuca Plate and do not occur in cores collected 90 km away at a similar site on the Explorer Plate. The record of subduction-related earthquake turbidite sequences is not complete at the Juan de Fuca study area and no reconstruction of megathrust quake periodicity is thus possible using this site alone. These results indicate that strong ground shaking is probably not experienced during large subduction earthquakes on the Explorer Plate.
Summary(Plain Language Summary, not published)
The history of very large subduction zone earthquakes on the western North American margin has been established through analysis of sedimentary deposits of the continental slope that record the events in turbidite sequences. Details and the geographic limits of areas affected by shaking by large earthquakes are not well constrained in the northern portion of the subduction zone including the northern Juan de Fuca Plate and the Explorer Plate. New results presented here are the first attempt to constrain large earthquake shaking on the boundary between these plates and determine if the Explorer Plate experiences strong shaking during very large quakes. These initial results suggest that the Explorer Plate does not experience strong shaking during subduction events.