Structural features and shear-velocity structure of the "Pacific Anomaly''

doi:10.1029/2008JB005814

	Structural features and shear-velocity structure of the "Pacific Anomaly''
	He, Yumei 1,2; Wen, Lianxing 1
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2009-02-18
卷号	114
ISSN号	2169-9313
DOI	10.1029/2008JB005814
文献子类	Article
英文摘要	We constrain structural features and shear-velocity structure of a low-velocity anomaly in the lower mantle beneath the Pacific (we term it the "Pacific Anomaly'') on the basis of forward travel time and waveform modeling of the observed direct S, Sdiff, ScS, SKS, and SKKS phases sampling a great arc across the anomaly from eastern Eurasia to southern South America. After correction for the effects of earthquake mislocation and the seismic heterogeneities outside the Pacific Anomaly, seismic observations suggest that the Pacific Anomaly along the great arc consists of at least two separated portions with a 740-km-wide gap between them. The western portion of the anomaly is about 1050 km wide, extends at least 740 km above the core-mantle boundary (CMB), and exhibits a trapezoidal shape with lateral dimensions increasing slightly with depth. The velocity structure of the western portion varies from -3.0% at the top (740 km above the CMB) to -3.5% at 100 km above the CMB and an average shear-velocity reduction of -5% in the bottom 100 km of the mantle. The eastern portion of the anomaly reaches at least 340 km above the CMB beneath the mid-Pacific with an 1800-km-wide base and has a uniform velocity reduction of -3%. Waveform modeling further suggests a very low velocity layer with a shear-velocity reduction of -10% located at the edge of the western portion of the anomaly. Combining the latest results from others, we present a general picture of structural and velocity structures of the Pacific Anomaly. The structural and velocity features suggest that the anomaly represents a cluster of metastable thermo-chemical piles.
WOS关键词	CORE-MANTLE BOUNDARY ; EARTHS MANTLE ; 3-DIMENSIONAL STRUCTURE ; AFRICAN SUPERPLUME ; SEISMIC EVIDENCE ; BENEATH AFRICA ; HYBRID METHOD ; WAVE ; MODEL ; BASE
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000263614200002
资助机构	National Science Foundation of China(40774041 ; National Science Foundation of China(40774041 ; NSF(0609717) ; NSF(0609717) ; 40434012) ; 40434012) ; National Science Foundation of China(40774041 ; National Science Foundation of China(40774041 ; NSF(0609717) ; NSF(0609717) ; 40434012) ; 40434012) ; National Science Foundation of China(40774041 ; National Science Foundation of China(40774041 ; NSF(0609717) ; NSF(0609717) ; 40434012) ; 40434012) ; National Science Foundation of China(40774041 ; National Science Foundation of China(40774041 ; NSF(0609717) ; NSF(0609717) ; 40434012) ; 40434012)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/71926]
专题	中国科学院地质与地球物理研究所
通讯作者	He, Yumei
作者单位	1.SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA 2.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earths Deep Interior, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	He, Yumei,Wen, Lianxing. Structural features and shear-velocity structure of the "Pacific Anomaly''[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2009,114.
APA	He, Yumei,&Wen, Lianxing.(2009).Structural features and shear-velocity structure of the "Pacific Anomaly''.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,114.
MLA	He, Yumei,et al."Structural features and shear-velocity structure of the "Pacific Anomaly''".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 114(2009).