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TitreFrontal ridge slope failure at the northern Cascadia margin: Margin-normal fault-and gas hydrates control
AuteurLópez, C; Spence, G; Hyndman, R; Kelley, D
SourceGeological Society of America, Abstracts With Programs vol. 38, no. 11, 2010 p. 967-970, (Accès ouvert)
Séries alt.Secteur des sciences de la Terre, Contribution externe 20080292
ÉditeurGeological Society of America
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceColombie-Britannique; Région extracotière de l'ouest
SNRC92B; 92E; 92F; 92L
Lat/Long OENS-130.0000 -122.0000 51.0000 48.0000
Sujetsbathymétrie; analyses de la stabilité des pentes; glissements de pentes; stabilité des pentes; caractéristiques structurales; analyses structurales; failles; dorsales sous-marines; gaz; hydrate; hydrocarbures; combustibles fossiles; géologie marine
Illustrationslocation maps; profiles
ProgrammeLes hydrates de gaz - carburant de l'avenir?
Diffusé2010 10 12
Résumé(disponible en anglais seulement)
There are numerous large sedimentary slump features near the base of the slope of the northern Cascadia accretionary margin off Vancouver Island. One 2 km wide collapse structure with a 250 m high headwall located has been studied by multi-beam bathymetry and a single-channel seismic reflection grid. , . Migrated seismic reflection lines on the frontal ridge image multiple 15 to 75 m high seafloor scarps perpendicular to the margin that are the seafloor expressions of normal faults that cut deeply into the sediment section.. Two of the largest faults are aligned with the sidewalls of the slump indicating that the lateral extent of slumping is fault-controlled. Marine gas hydrate is present beneath the ridge, based on a widespread hydrate Bottom-Simulating Reflector (BSR), on high velocities determined by ocean bottom seismograph data, and on sediment core samples and downhole logs collected by the Integrated Ocean Drilling Program at Site U1326. The depth of the BSR coincides closely to the estimated depth of ~255 m for the depth of the glide plane beneath the slump suggesting that the base of slumping is related to the contrast between strong hydrate-cemented sediments above the BSR and underlying weak sediments containing free gas. Strong earthquake shaking on this convergent margin likely provides the trigger for the slope failure.