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Localized temporal variation of Earth’s inner-core boundary from high-quality waveform doublets |
Danhua Xin1, Xiaodong Song1,2, Tao Wang1 |
1 Institute of Geophysics and Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
2 Department of Geology, University of Illinois at Urbana-Champaign, Champaign, USA |
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Abstract The topography of the inner core is crucial to understand its growth process and interaction with the geodynamo. With the accuracy of teleseismic waveform doublets in determining the travel-time shifts between PKPcd and PKPdf inner-core phases, we examined the temporal change of the inner-core boundary sampled by new earthquake doublets that occurred in the Western Pacific and those previously found from the South Sandwich Islands. The receiver stations are those within the distance range of 128–142 from the hypocenters of the waveform doublets. Our results suggest that temporal changes in PKPcd-PKPdf differential times are very subtle except some isolated regions under central America and Africa. The observations may indicate localized topography of the inner core and/or the inner-core boundary as transient slurry in isolated regions.
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Fund:Natural Science Foundation of China (41330209), the Ministry of Science and Technology of China (2014CB845901), and the China Earthquake Administration. |
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[1] |
Yongge Wan, Zheng-kang Shen, Min Wang, Yuehua Zeng, Jichao Huang, Xiang Li, Huawei Cui, Xiwei Gao. Co-seismic fault geometry and slip distribution of the 26 December 2004, giant Sumatra–Andaman earthquake constrained by GPS, coral reef, and remote sensing data[J]. Earthquake Science, 2015, 28(3): 187-195. |
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