2021 Fiscal Year Final Research Report
Examination of High-frequency excitation characteristics of the intraplate earthquakes
| Project/Area Number |
20K20290
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| Project/Area Number (Other) |
17H06215 (2017-2019)
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| Research Category |
Grant-in-Aid for Challenging Research (Pioneering)
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| Allocation Type | Multi-year Fund (2020)
Single-year Grants (2017-2019) |
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| Research Field |
Architecture, Building engineering, and related fields
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| Research Institution | Hokkaido University |
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Principal Investigator |
Takai Nobuo 北海道大学, 工学研究院, 准教授 (10281792)
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| Co-Investigator(Kenkyū-buntansha) |
重藤 迪子 九州大学, 人間環境学研究院, 助教 (90708463)
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| Project Period (FY) |
2017-06-30 – 2022-03-31
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| Keywords | プレート内地震 / プレート境界地震 / 短周期地震動 |
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| Outline of Final Research Achievements |
The source characteristics of plate boundary earthquakes and inland crustal earthquakes have been examined in detail due to their frequency. But there is a small number of examples of intraplate earthquakes. We compared the source characteristics of interplate and intraplate earthquakes of almost the same scale and epicenter and showed that high-frequency excitation in intraplate earthquakes is strong. We also compared intraplate earthquakes with different depths and showed that deep hypocenters have stronger high-frequency excitation than shallow hypocenters. The 2018 Hokkaido Eastern Iburi Earthquake was relatively deep and had strong high-frequency excitation source characteristics. We estimated the underground structural model around the area where the dangerous seismic motion occurred, was estimated. We clarified that the causes of dangerous seismic motion are the ground amplification characteristics of the surface layer and the non-linear effect during the mainshock.
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| Free Research Field |
地震工学
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| Academic Significance and Societal Importance of the Research Achievements |
地震による構造物被害を減らすには，来たる地震動に対して適切な設計をもって構造物を設置しなければならない．近年ではプレート境界で発生する大地震・巨大地震によるいわゆる長周期地震動による被害・観測記録が蓄積されつつあり，予測精度も向上している．一方の短周期地震動を適切に予測するための，震源特性の検討は不十分である．日本海溝・千島海溝で発生したプレート境界で発生する地震とプレート内で発生する地震の震源特性を比較し，プレート内で発生する地震で短周期地震動を強く発生させる事を明らかにした．本手法と同様にして，今後プレート内地震の検討事例を蓄積することで，より正確な短周期地震動の予測が可能となる．
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