DOI: 10.1016/j.epsl.2020.116569
论文题名: Significant geometric variation of the subducted plate beneath the northernmost Cascadia subduction zone and its tectonic implications as revealed by the 2014 MW 6.4 earthquake sequence
作者: Hutchinson J. ; Kao H. ; Riedel M. ; Obana K. ; Wang K. ; Kodaira S. ; Takahashi T. ; Yamamoto Y.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 551 语种: 英语
中文关键词: Cascadia subduction zone
; Explorer plate
; megathrust
; Nootka fault zone
; plate deformation
英文关键词: Deformation
; Earthquakes
; Geometry
; Parallel flow
; Cascadia subduction zone
; Depth distribution
; Earthquake sequences
; Geometric variations
; Seismic activity
; Subducting plate
; Subduction interface
; Tectonic implications
; Faulting
; deformation
; earthquake event
; fault zone
; geometry
; plate boundary
; plate tectonics
; subduction
; subduction zone
; thrust
; Cascadia Subduction Zone
; Pacific Ocean
英文摘要: At the northernmost extent of the Cascadia subduction zone, the Explorer plate subducts at approximately 2 cm/yr, less than half the rate of the Juan de Fuca plate to the south. The boundary between these two plates is known as the Nootka fault zone, which is one of the focuses of the Seafloor Earthquake Array Japan-Canada Cascadia Experiment (SeaJade). During this survey, an MW 6.4 earthquake occurred on 24 April 2014. This event and the subsequent aftershocks (referred to as the Nootka Sequence) reveal an approximately 40-km-long subducted fault within the Explorer Plate to the north of the Nootka fault zone. We infer that the fault is a subducted conjugate fault because of its nearly identical orientation to those seaward of the subduction front within the Nootka fault zone. The depth distribution and focal mechanisms of the aftershocks indicate significant margin-parallel deformation of the subducting plate. The subduction interface at the Nootka Sequence fault has been deflected downward to the northwest from a depth of approximately 15 – 25 km over a distance of 25 km. We propose two possible scenarios that are modified from previously suggested slab-tear model with induced margin-parallel mantle flow to explain the significant deformation of the young, warm subducting Explorer plate. To the northwest of this change in slab geometry, a lack of seismic activity above the plate interface indicates that the Explorer plate has partially decoupled from the overriding North America plate. We conclude that the geometric variation separating the southern Explorer plate from the north, along with decoupling and a possible intraslab tear, may be a significant combination to resist the propagation of a megathrust rupture across this boundary. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165045
Appears in Collections: 气候变化与战略
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作者单位: School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada; Pacific Geoscience Centre, Geological Survey of Canada, Natural Resources Canada, Sidney, BC V8L 4B2, Canada; GEOMAR Helmholtz-Centre for Ocean Research Kiel, Kiel, Germany; Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan
Recommended Citation:
Hutchinson J.,Kao H.,Riedel M.,et al. Significant geometric variation of the subducted plate beneath the northernmost Cascadia subduction zone and its tectonic implications as revealed by the 2014 MW 6.4 earthquake sequence[J]. Earth and Planetary Science Letters,2020-01-01,551