Research on the scatter features of the PKiKP/PcP amplitude ratio and the inner core boundary density contrasts beneath Northeast Asia

作     者：Haodong ZHANG Yinshuang AI Yumei HE Haodong ZHANG;Yinshuang AI;Yumei HE

作者机构：Key Laboratory of Earth and Planetary PhysicsInstitute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China CAS Center for Excellence in Tibetan Plateau Earth SciencesBeijing 100049China University of Chinese Academy of SciencesBeijing 100101China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2021年第64卷第5期

页      面：716-727页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：supported by the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB18000000) the National Natural Science Foundation of China(Grant No.41125015)。 

主　　题：Northeast Asia Inner core boundary PKiKP/PcP amplitude ratio Density contrast 

摘      要：Quantifying the density contrasts of the Earth’s inner core boundary(ICB)is crucial to understand core-mantle coupling and the generation of the geodynamo.The PKiKP/PcP amplitude ratio is commonly used to obtain the density contrast at the ICB,but its applications are limited by scattered observed data.In this study,we selected the PKiKP and PcP phases reflected at the same region of inner-core and core-mantle boundaries beneath Northeast Asia from different earthquakes for the first time,and the observations suggested that the PKiKP/PcP amplitude ratio is widely scattered.We also compared the PKiKP and PcP amplitudes,which demonstrated that the scatter cannot be attributed only to ICB anomalies but might also arise from raypath differences and heterogeneities throughout the crust and mantle.By fitting the observed PKiKP/PcP amplitude ratio,we obtained a density contrast of approximately 0.65 g cm^(-3) and a compressional velocity contrast of approximately 0.87 km s^(-1) at the ICB beneath Northeast Asia.The larger contrast values indicate the possible occurrence of local crystallization occurring at the inner core surface.