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Check of Earth’s free oscillations excited by Sumatra-Andaman Large Earthquake and discussions on the anisotropy of inner core |
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| Authors: | Lei XiangE Sun HePing Hsu HouTse Shi YaoLin |
| Institution: | 1. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;Laboratory of Computational Geodynamics, Graduate University of Chinese Academy of Sciences, Beijing 100049, China 2. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China 3. Laboratory of Computational Geodynamics, Graduate University of Chinese Academy of Sciences, Beijing 100049, China |
| Abstract: | Sumatra-Andaman Large Earthquake on Dec. 26, 2004 generated not only the Indian Ocean Tsunami but also the Earth’s free oscillations (EFO). The signals of Earth’s free oscillations were perfectly recorded by the superconducting gravimeter C0-32 at Wuhan station in China. After the pre-treatment and spectral analysis on the observational data from Wuhan station, we obtained more than ninety EFO modes including 42 fundamental modes, 2 radial modes and 49 harmonic modes. On the basis of the discussions on some observed harmonic modes and abnormal splitting phenomena, we considered that the real rigidity might be lower than the theoretical prediction of PREM model in the inner core and however the anisotropy of compressive wave was brightly higher than the present estimations in the inner core. This suggested that the anisotropy of the inner core could be much more complicated than our present understanding, and there might be some new geophysical phenomena in the formation process of the inner core. Supported jointly by the National Natural Science Foundation of China (Grant Nos. 40404005 and 40374029) and the Excellent Prize of President Scholarship and Hundred Talents Program of the Chinese Academy of Sciences |
| Keywords: | Sumatra-Andaman Large Earthquake Earth's free oscillations superconducting gravimeter abnormal spectral splitting anisotropy of inner core |
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