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TitreTemporal evolution of an episodic tremor and slip event along the northern Cascadia margin
AuteurDragert, H; Wang, K
SourceJournal of Geophysical Research vol. 116, B12406, 2011 p. 1-12, https://doi.org/10.1029/2011JB008609
Année2011
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110268
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1029/2011JB008609
Mediapapier; en ligne; numérique
Formatspdf
ProvinceColombie-Britannique
SNRC92B; 92C; 92F; 92G
Lat/Long OENS-126.0000 -121.5000 49.5000 46.0000
Sujetstectonique de plaques; milieux tectoniques; interprétations tectoniques; frontières de plaques; marges continentales; tectonique
Illustrationslocation maps; plots; tables
ProgrammeTargeted Hazard Assessments in Western Canada, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Episodic tremor and slip (ETS) have now been observed along the northern Cascadia margin for over 15 years. Recent densification of GPS coverage and the introduction of Gladwin borehole strainmeters (BSMs) under the Plate Boundary Observatory have enabled the derivation of improved slip models and have allowed more detailed monitoring of the migration of the slip surface during prolonged ETS events. For this study we examine the along-strike migration of the May 2008 ETS as determined from the GPS and BSM observations. GPS sites overlying the 30 km depth contour of the subducting plate interface show that the slip initiates west of northern Puget Sound and propagates bidirectionally. Shear strain time series at regional BSM sites confirm this bidirectional expansion of the slip zone. In a simple model of along-strike propagation constrained by the GPS and BSM time series, the speed of the northwest propagation varies from 8, then to 2, and then to 15 km/d, but the speed of the south propagation stays at 6 km/d. The tremors observed for this ETS episode show a similar bidirectional migration pattern and similar changes in northwest migration velocity, but the migration front is slightly ahead of the slip propagation front. These results provide important information for understanding the mechanics of ETS.
GEOSCAN ID289568