| Project/Area Number |
18K03786
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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 | Yokohama City University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
武村 俊介 東京大学, 地震研究所, 助教 (10750200)
中原 恒 東北大学, 理学研究科, 准教授 (20302078)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | 地震波 / 振幅の揺らぎ / ばらつき / 地殻構造 / ランダム不均質性 / 地殻構造のランダム不均質性 |
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| Outline of Final Research Achievements |
We investigated the characteristics of the fluctuations of seismic-wave amplitudes and travel times due to short-wavelength random heterogeneity of crustal structure on the basis of numerical simulation of seismic wave propagation. We confirmed that the fluctuations of P-wave and S-wave amplitudes increase with distance near the hypocenter, and the characteristics are more noticeable at higher frequencies. Within the range of parameters used in this study, the larger the correlation distance and the magnitude of the fluctuations of the short-wavelength random heterogeneity, the larger the amplitude fluctuations are demonstrated. In addition, we found that the travel-time fluctuation also increases with the hypocentral distance. It was confirmed that the travel-time fluctuations (standard deviation) of P-waves are modeled by the predictions of Markov approximation theory.
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| Academic Significance and Societal Importance of the Research Achievements |
S波の振幅のばらつきの特性の把握は、地震工学における地震動予測の高度化（予測誤差の評価）の観点からも重要視されている。本研究では、地殻構造が短波長ランダム不均質性を有する場合、地震波伝播の物理特性から、地震動予測に一定レベルの不確定性が発生することを示した。今後、地殻構造の短波長ランダム不均質性を正確に把握することで、物理モデルに基づく予測誤差を反映させた地震動予測が可能になるものと期待される。
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