气候变化领域集成服务门户(CCPortal): Poloidal- and Toroidal-Mode Mantle Flows Underneath the Cascadia Subduction Zone

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DOI	10.1029/2020GL087530
	Poloidal- and Toroidal-Mode Mantle Flows Underneath the Cascadia Subduction Zone
	Zhu H.; Li X.; Yang J.; Stern R.J.; Lumley D.E.
发表日期	2020
ISSN	0094-8276
卷号	47 期号:14
英文摘要	Several hypotheses have been proposed to explain intriguing circular shear wave splitting patterns in the Pacific Northwest, invoking either 2-D entrained flows or 3-D return flows. Here, we present some hitherto unidentified, depth-dependent anisotropic signatures to reconcile different conceptual models. At depths shallower than 200 km, the fast propagation directions of seismic waves to the west of the Rocky Mountain are aligned sub-parallel to the subduction direction of the Juan de Fuca and Gorda Plates. This pattern is consistent with previous onshore/offshore shear wave splitting measurements and indicates that 2-D entrained flows dominate at shallower depths. From 300 to 500 km, two large-scale return flows are revealed, one circulating around Nevada and Colorado and the other running around the edge of the descending Juan de Fuca slab. These observations suggest the development of toroidal-mode mantle flows, driven by the fast rollback of the narrow, fragmented Juan de Fuca and Gorda slabs. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Shear waves; Cascadia subduction zone; Conceptual model; Depth dependents; Entrained flow; Pacific Northwest; Propagation direction; Rocky Mountains; Shear wave splitting; Shear flow; S-wave; seismic wave; subduction; subduction zone; wave direction; wave propagation; wave splitting; Cascadia Subduction Zone; Colorado; Nevada; Pacific Northwest; Pacific Ocean; Rocky Mountains; United States
语种	英语
来源期刊	Geophysical Research Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/170131
作者单位	Department of Geosciences, The University of Texas at Dallas, Richardson, TX, United States; Department of Physics, The University of Texas at Dallas, Richardson, TX, United States
推荐引用方式 GB/T 7714	Zhu H.,Li X.,Yang J.,et al. Poloidal- and Toroidal-Mode Mantle Flows Underneath the Cascadia Subduction Zone[J],2020,47(14).
APA	Zhu H.,Li X.,Yang J.,Stern R.J.,&Lumley D.E..(2020).Poloidal- and Toroidal-Mode Mantle Flows Underneath the Cascadia Subduction Zone.Geophysical Research Letters,47(14).
MLA	Zhu H.,et al."Poloidal- and Toroidal-Mode Mantle Flows Underneath the Cascadia Subduction Zone".Geophysical Research Letters 47.14(2020).