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TitreUpper crustal structure of southwestern British Columbia from the 1998 Seismic Hazards Investigation in Puget Sound
AuteurRamachandran, K; Dosso, S E; Zelt, C A; Spence, G D; Hyndman, R D; Brocher, T M
SourceJournal of Geophysical Research vol. 109, no. B9, B09303, 2004, 14 pages, https://doi.org/10.1029/2003JB002826 (Accès ouvert)
Année2004
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2003120
ÉditeurWiley-Blackwell
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1029/2003JB002826
Mediapapier; en ligne; numérique
Formatspdf
ProvinceColombie-Britannique
SNRC92B; 92C/01; 92C/02; 92C/03; 92C/06; 92C/07; 92C/08; 92C/09; 92C/10; 92C/11; 92C/14; 92C/15; 92C/16; 92F/01; 92F/02; 92F/03; 92F/06; 92F/07; 92F/08; 92F/09; 92F/10; 92F/11; 92F/14; 92F/15; 92F/16; 92G
Lat/Long OENS-125.2500 -122.0000 50.0000 47.5000
Sujetsséismologie; vitesse des ondes sismiques; ondes sismiques; ondes P; zones sismiques; sismicité; levés de refraction sismiques; établissement de modèles; anomalies; tectonophysique; croûte continentale; études de la croûte; structure de la croûte; épaisseur de la croûte; accretion; terrains; bassins; développement du bassin; bassins sédimentaires; failles; tendances structurelles; secousses séismiques; microsecousses; sutures; failles, chevauchement; gabbros; faciès; Zone de subduction de Cascadia ; Complexe de Metchosin Igneous ; Terrane de Wrangellia ; Complexe de Coast Plutonic ; Bassin de Clallam ; Bassin de Port Townsend ; Bassin de Georgia ; Bassin de Sequim ; Terrane de Crescent ; Terrane de Pacific Rim ; Ceinture de Cowichan Thrust And Fold ; Faille d'Outer Islands ; géophysique; tectonique; géologie structurale
Illustrationssketch maps; geophysical images; models; profiles; geophysical maps
ProgrammeCRSNG Conseil de recherches en sciences naturelles et en génie du Canada
Diffusé2004 09 09
Résumé(disponible en anglais seulement)
This paper applies nonlinear three-dimensional travel time tomography to refraction data recorded during the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) to derive the first large-scale, high-resolution upper crustal velocity model for southwestern British Columbia. A minimum structure P wave velocity model is constructed using 175,000 first arrival travel times picked from data recorded by 58 temporary onshore stations. The model details forearc crustal structures related to terrane accretion and subsequent basin formation to a depth of about 10 km. The Metchosin igneous complex (correlative with the Eocene Crescent?Siletz Terrane in Washington) is imaged as a laterally extensive WNW trending high-velocity anomaly underlying southernmost Vancouver Island and much of the Strait of Juan du Fuca. Northeast of the Strait of Georgia, the southwesterly dip of the contact between the Wrangellia terrane rocks of Vancouver Island and the Coast Plutonic Complex suggests Wrangellia rocks are down-faulted against the plutonic complex. At the southwestern end of the Strait of Juan de Fuca, the 50 km long WNW trending Clallam basin has a maximum thickness of 5-6 km. Near the eastern end of the Strait of Juan de Fuca, Port Townsend basin has an inferred thickness of approximately 4-5 km. The southern end of the 9 km thick Georgia basin is bounded by a high-velocity basement ridge. Beneath the Strait of Georgia, clusters of well?located earthquakes have a prominent NW trend and coincide spatially with rapid lateral velocity changes. Clusters of microearthquakes there are associated with the intersection of several east trending structural highs within this NW trend.
GEOSCAN ID214655