气候变化领域集成服务门户(CCPortal): Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm

CCPortal

DOI	10.1029/2020JB020545
	Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm
	Stephenson J.; Tkalčić H.; Sambridge M.
发表日期	2021
ISSN	21699313
卷号	126 期号:1
英文摘要	The model of cylindrical anisotropy in the inner core (IC) states that seismic rays traveling parallel to the Earth's rotational axis travel faster than those parallel to the equator. There have been continuing discrepancies in estimates of the strength and orientation of anisotropy, with some evidence suggesting that such a model may not be supported by available data. Here, we scrutinize the radial dependence of anisotropy within the IC, where the nature of anisotropy has been shown to change anywhere between a 300 and 800 km radius. We use recent travel time data from the International Seismological Centre in conjunction with the neighborhood algorithm to provide a robust means of testing this idea, through examination of an ensemble of models that satisfactorily fit the data. This can be done with no explicit regularization and without the need for subjective choices associated with binning of phase data. In addition, uncertainty bounds are calculated for anisotropic parameters using a likelihood ratio approach. We find evidence to suggest that commonly employed spatial averaging (binning) methods may be detrimental to obtaining reliable results. We conclude that there is no significant change in the strength of anisotropy with depth in the IC. Instead, we find a change in the slow direction of anisotropy to 54° within the innermost IC at an ∼650 km radius with fast direction parallel to the Earth's rotational axis. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	anisotropy; earth's inner core; innermost inner core; neighborhood algorithm; seismology
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187421
作者单位	Research School of Earth Sciences, The Australian National University, Canberra, ACT, Australia
推荐引用方式 GB/T 7714	Stephenson J.,Tkalčić H.,Sambridge M.. Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm[J],2021,126(1).
APA	Stephenson J.,Tkalčić H.,&Sambridge M..(2021).Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm.Journal of Geophysical Research: Solid Earth,126(1).
MLA	Stephenson J.,et al."Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm".Journal of Geophysical Research: Solid Earth 126.1(2021).