2023 Fiscal Year Final Research Report
Breaking away from "Earthquake = shear failure": An attempt to estimate subtle non-double couple component through a new method
| Project/Area Number |
20K04141
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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 | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
Imanishi Kazutoshi 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 副研究部門長 (70356517)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 非せん断破壊 / 逐次相対法 / モーメントテンソル解 / 臨時観測 |
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| Outline of Final Research Achievements |
In this study, we developed a method that iteratively applies Dahm's (1996) relative moment tensor inversion to earthquakes within a cluster, improving the accuracy of individual moment tensor solutions as well as the relative accuracy between earthquakes. This method resolves the inherent issue of relative methods, where reliable results cannot be obtained if the reference earthquake's moment tensor solution is inaccurate. We applied this method to several earthquake sequences and demonstrated that it can estimate small non-double couple components of earthquakes with sufficient accuracy.
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| Free Research Field |
地震学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究で開発した手法を複数の地震活動に適用することで、通常地震の中にも微弱ながらも有意な非せん断破壊成分を持つ地震が存在することが明らかになった。この成果は半世紀以上にわたり認められてきた「地震＝断層運動」という既存概念を書き換えることに繋がる。非せん断破壊成分は流体の関与、大地震発生前の震源核形成、空隙の多い断層帯内での圧密などとの関連が予想される。本研究で開発した手法を活用していく事で、これまで踏み込むことができなかった微視的な地殻プロセスの実態に迫ることができると考える。
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