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TitreSeismicity, geodynamics and seismic hazard in Yukon-western Northwest Territories
AuteurLeonard, L; Hyndman, R D; Cassidy, J F; Allen, T; Rogers, G C; Kao, H; Adams, J
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 39, 2016 p. 51-52
LiensDownload entire publication / téléchargement de la publication au complet
Année2016
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160028
ÉditeurAssociation géologique du Canada
Réunion"Margins Through Time" Geological Association of Canada - Mineralogical Association of Canada Joint Annual Meeting; Whitehorse, YT; CA; juin 1-3, 2016
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceYukon; Territoires du Nord-Ouest
Sujetsfailles; secousses séismiques; marges continentales; études de la croûte; études séismiques; modèles tectoniques; sismicité; failles, chevauchement; epicentres; formation de failles; Zone de faille d'Eskimo Lakes ; tectonique
ProgrammeOuest du Canada, risque géoscience, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
There is substantial earthquake occurrence and hazard in Yukon and western Northwest Territories that is not always appreciated. We describe the distribution of past earthquakes and hazard estimates based on the earthquake data file, geophysical and geological constraints and geodynamic models. There is exceptional seismicity in SW Yukon, adjacent Alaska and BC where the Yakutat terrane is colliding with the continental margin in the Gulf of Alaska, pushing up the spectacular St. Elias Mountains including Mt. Logan, Canada¿s highest mountain. The region has had numerous recorded magnitude 7 to 8 earthquakes in adjacent Alaska. Less well known is the strong seismicity in the Mackenzie Mountains, Richardson Mountains, and the Beaufort Sea regions, with a number of magnitude 6 to 7 recorded earthquakes. The earthquake record and high-precision GPS data support a tectonic model of the Yakutat terrane collision driving the northern Cordillera Yukon block to the north-northeast. The collision drives transpression in SW Yukon, thrust faulting in the Mackenzie Mountains, and dextral strike-slip faulting in the Richardson Mountains region that may extend northward to the continental margin through the Eskimo Lakes Fault zone. The Richardson dextral motion coupled with sinistral motion in the Canning displacement zone in eastern Alaska implies an intervening northward-moving crustal block and active convergence at the Beaufort Sea continental margin. Although there have been no historical large events, the Mackenzie Delta thrust front may be capable of infrequent but large thrust earthquakes with associated tsunamis. The northerly motion also may be responsible for the concentration of seismicity in the Beaufort Sea. There is steady improvement but still limited seismograph station coverage in northwestern Canada which limits the epicentre accuracies, correlations with mapped faults, and calculation of other earthquake parameters. Only earthquakes above about M3 are consistently located, and there is limited depth resolution and rupture mechanism determination. There have been significant recent advances in modelling the ground shaking hazard in the area, from better earthquake data, GPS data, and tectonic models. There are also better models that estimate the attenuation of strong ground shaking with distance, but the hazard characterizations are still only very regional. Future seismic hazard models for the region would benefit from an improved seismotectonic model of the region based on neotectonic evidence of active faulting and enhanced seismic and GPS observations.
Résumé(Résumé en langage clair et simple, non publié)
Il y a un risque sismique importante au Yukon et dans l'ouest des Territoires du Nord-Ouest qui ne sont pas toujours apprécié. Nous décrivons la répartition des séismes passés et les estimations de risque sur la base du fichier de données de tremblement de terre , les contraintes géophysiques et géologiques et des modèles géodynamiques . Il y a eu des progrès significatifs dans la modélisation de la secousse danger dans la région, de meilleures données sismiques, des données GPS , et les modèles tectoniques . Nous décrivons des améliorations aux modèles de risques sismiques pour la région en utilisant un modèle sismotectonique amélioré basé sur des preuves néotectonique des failles actives et améliorées observations sismiques et GPS .
GEOSCAN ID298720