2018 Fiscal Year Annual Research Report
メルト輸送過程を考慮した地球内核成長モデルによる地震波異方性の成因解明
| Project/Area Number |
18K13632
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ラスブレイス マリン 東京工業大学, 地球生命研究所, 研究員 (90802314)
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| Project Period (FY) |
2018-04-01 – 2019-03-31
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| Keywords | geodynamics, Earth / deep Earth / inner core / two-phase dynamics / crystallisation |
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| Outline of Annual Research Achievements |
The goal of the project was to determine the range of parameters for which melt is trapped in depth and the system is unstable and instabilities should develop, and to describe and quantify the deformation induced by such flows.
I developed a semi-analytical model, based on two-phase flow dynamics to study the compaction of the inner core as it is growing. Following previous study of Sumita et al. (1986), I modeled the compaction of a self-gravitating sphere, while the sphere is growing from crystallization at the top. The system allow for variations of two main parameters: growth rate and compaction length.
To explore the possible dynamics for the Earth’s inner core, I studied three different set-up for the growth: constant growth rate, realistic growth from Labrosse et al. 2014 and supercooled core from Huguet et al 2018. As the compaction length for the inner core of the Earth is thought to be smaller than 100km, the most promising scenario to trap melt in the system is the supercooled core, trapping up to 30% of melt in the depth of the core. This amount of melt is too large for the observations of shear waves in today’s inner core, which help us constraining reasonnable upper bound for supercooling.
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