气候变化领域集成服务门户(CCPortal): Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California

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DOI	10.1093/gji/ggw271
	Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California
	Ramsay, Joseph; Kohler, Monica D.; Davis, Paul M.; Wang, Xinguo; Holt, William; Weeraratne, Dayanthie S.
通讯作者	Kohler, MD (通讯作者)
发表日期	2016
ISSN	0956-540X
EISSN	1365-246X
起始页码	244
结束页码	258
卷号	207 期号:1
英文摘要	SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analysed for shear wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 km west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper-mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range.
关键词	SEISMIC ANISOTROPY MANTLE FLOW OLIVINE POLYCRYSTALS JOINT INVERSION UNITED-STATES FINITE STRAIN WAVE SHEAR BENEATH DYNAMICS
英文关键词	Body waves; Seismic anisotropy; Continental margins: transform; Dynamics of lithosphere and mantle; Pacific Ocean
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000384651200017
来源期刊	GEOPHYSICAL JOURNAL INTERNATIONAL
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258849
推荐引用方式 GB/T 7714	Ramsay, Joseph,Kohler, Monica D.,Davis, Paul M.,et al. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California[J]. 中国科学院青藏高原研究所,2016,207(1).
APA	Ramsay, Joseph,Kohler, Monica D.,Davis, Paul M.,Wang, Xinguo,Holt, William,&Weeraratne, Dayanthie S..(2016).Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California.GEOPHYSICAL JOURNAL INTERNATIONAL,207(1).
MLA	Ramsay, Joseph,et al."Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California".GEOPHYSICAL JOURNAL INTERNATIONAL 207.1(2016).