2023 Fiscal Year Final Research Report
High-resolution mapping of the upper mantle discontinuities with Bayesian inferences
| Project/Area Number |
20K04096
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 上部マントル / 不連続面 / 表面波 / レシーバ関数 / トモグラフィー / ベイズ推定 |
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| Outline of Final Research Achievements |
We developed and applied a method for estimating anisotropic S-wave speed structures and discontinuities in the upper mantle beneath a seismic station using a nonlinear inversion based on Bayesian inferences, jointly using phase velocities of multimode surface waves (useful for recovering 3-D S-wave speed structure), and body wave receiver functions (useful for detecting seismic discontinuities). The method was applied to a large number of stations in Australia, where large amounts of high-quality seismic waveform data are available, and we demonstrated its effectiveness in estimating the spatial distribution of major discontinuities such as the Moho and the Lithosphere-Asthenosphere Boundary. We also performed surface wave tomography using a large number of observed seismic records in continental regions, including North America and eastern Eurasia, and constructed detailed 3-D S-wave velocity models for each region.
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| Free Research Field |
地震学
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| Academic Significance and Societal Importance of the Research Achievements |
プレートの成長・進化や水平移動のメカニズムを理解する上で，上部マントル内部の境界層と地震波速度の異方的性質は重要な鍵となる．しかし，モホ面やマントル遷移層等の顕著な不連続面に比べ，リソスフェアやアセノスフェアの深さに見られる不連続面での速度変化は比較的小さい場合が多く，その検出は容易ではない．本研究では，異なる感度を有する実体波や表面波の各種観測情報を用いて，上部マントル内の異方的S波速度構造の復元と不連続面の推定に向けた手法を開発し，試験的応用を試みた．一連の成果は，プレート内部やプレート底面およびアセノスフェアに見られる不連続面の一層の理解の礎になるものと期待される．
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