DOI: 10.1016/j.epsl.2018.01.002
Scopus记录号: 2-s2.0-85044310202
论文题名: Stress rotation across the Cascadia megathrust requires a weak subduction plate boundary at seismogenic depths
作者: Li D. ; McGuire J.J. ; Liu Y. ; Hardebeck J.L.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 485 起始页码: 55
结束页码: 64
语种: 英语
英文关键词: Cascadia Initiative OBS
; linear matrix inequalities (LMI)
; low effective friction coefficient
; Mendocino Triple Junction
; spatial stress rotation
; weak plate boundary zone
Scopus关键词: Friction
; Linear matrix inequalities
; Shear stress
; Tectonics
; Tribology
; Cascadia
; Effective friction coefficient
; Mendocino triple junctions
; Plate boundaries
; Stress rotation
; Faulting
; collision zone
; fault zone
; Pacific plate
; plate boundary
; seismograph
; strike-slip fault
; subduction zone
; thrust
; triple junction
; Cascadia Subduction Zone
; Pacific Ocean
英文摘要: The Mendocino Triple Junction region is the most seismically active part of the Cascadia Subduction Zone. The northward moving Pacific plate collides with the subducting Gorda plate causing intense internal deformation within it. Here we show that the stress field rotates rapidly with depth across the thrust interface from a strike-slip regime within the subducting plate, reflecting the Pacific plate collision, to a thrust regime in the overriding plate. We utilize a dense focal mechanism dataset, including observations from the Cascadia Initiative ocean bottom seismograph experiment, to constrain the stress orientations. To quantify the implications of this rotation for the strength of the plate boundary, we designed an inversion that solves for the absolute stress tensors in a three-layer model subject to assumptions about the strength of the subducting mantle. Our results indicate that the shear stress on the plate boundary fault is likely no more than about ∼50 MPa at ∼20 km depth. Regardless of the assumed mantle strength, we infer a relatively weak megathrust fault with an effective friction coefficient of ∼0 to 0.2 at seismogenic depths. Such a low value for the effective friction coefficient requires a combination of high fluid pressures and/or fault-zone minerals with low inherent friction in the region where a great earthquake is expected in Cascadia. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110034
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Dept. of Earth and Planetary Sciences, McGill University, Montreal, Canada; Dept. of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; U.S. Geological Survey, Menlo Park, CA, United States
Recommended Citation:
Li D.,McGuire J.J.,Liu Y.,et al. Stress rotation across the Cascadia megathrust requires a weak subduction plate boundary at seismogenic depths[J]. Earth and Planetary Science Letters,2018-01-01,485