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

Document Type


Department or Administrative Unit

Geological Sciences

Publication Date



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 ∼400 km above the CMB and are distributed between 30° and 45°N in latitude. The scatterers show the largest P-wave velocity perturbation of 1.0–1.2% in the center (160–180°E) and ∼0.5% to the west and east (140–160°E, 180–200°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.


This article was originally published in Physics of the Earth and Planetary Interiors. The full-text article from the publisher can be found here.

Due to copyright restrictions, this article is not available for free download from ScholarWorks @ CWU.


Physics of the Earth and Planetary Interiors


Copyright © 2016 Elsevier B.V. All rights reserved.