Strong seismic scatterers near the core-mantle boundary north of the Pacific Anomaly

Tomographic images have shown that there are clear high-velocity heterogeneities to the north of the Pacific Anomaly near the core-mantle boundary (CMB), but the detailed structure and origin of these heterogeneities are poorly known. In this study, we analyze PKP precursors from earthquakes in the...

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Bibliographic Details
Published in:Physics of the Earth and Planetary Interiors
Main Authors: Ma, Xiaolong, Sun, Xinlei, Wiens, Douglas A., Wen, Lianxing, Nyblade, Andrew, Anandakrishnan, Sridhar, Aster, Rick, Huerta, Audrey, Wilson, Terry
Format: Report
Language:English
Published: ELSEVIER SCIENCE BV 2016
Subjects:
Geochemistry & Geophysics
Seismic scatterers
PKP precursor
Subducted slabs
Lateral heterogeneities
Core-mantle boundary
SUBDUCTED OCEANIC-CRUST
DEEP EARTH DYNAMICS
LOW VELOCITY ZONES
LOWERMOST MANTLE
WAVE SCATTERING
PKP PRECURSORS
INNER-CORE
CHEMICAL HETEROGENEITY
ATTENUATION STRUCTURES
SYNTHETIC SEISMOGRAMS
Kamchatka Peninsula
Pacific
Antarc*
Antarctica
Kamchatka
Aleutian Islands
Online Access:http://ir.gig.ac.cn/handle/344008/54963
https://doi.org/10.1016/j.pepi.2016.01.007
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Summary:Tomographic images have shown that there are clear high-velocity heterogeneities to the north of the Pacific Anomaly near the core-mantle boundary (CMB), but the detailed structure and origin of these heterogeneities are poorly known. In this study, we analyze PKP precursors from earthquakes in the Aleutian Islands and Kamchatka Peninsula recorded by seismic arrays in Antarctica, and find that these heterogeneities extend similar to 400 km above the CMB and are distributed between 30 degrees and 45 degrees N in latitude. The scatterers show the largest P-wave velocity perturbation of 1.0-1.2% in the center (160-180 degrees E) and similar to 0.5% to the west and east (140-160 degrees E, 180-200 degrees E). ScS-S differential travel-time residuals reveal similar features. We suggest that these seismic scatterers are the remnants of ancient subducted slab material. The lateral variations may be caused either by different slabs, or by variations in slab composition resulting from their segregation process. (C) 2016 Elsevier B.V. All rights reserved.

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