Elucidation of low-activity active fault, targeting small surface ruptures associated with the 2016 Kumamoto earthquake
| Project/Area Number |
17H04730
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| Research Category |
Grant-in-Aid for Young Scientists (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Geography
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
Ishimura Daisuke 東京都立大学, 都市環境科学研究科, 助教 (00736225)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥16,900,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥3,900,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2018: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2017: ¥6,630,000 (Direct Cost: ¥5,100,000、Indirect Cost: ¥1,530,000)
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| Keywords | 2016年熊本地震 / 活断層 / 低活動度活断層 / トレンチ調査 / 古地震 / テフラ / 微小断層変位 / 布田川断層 / 熊本県 / 古地震履歴 / 地表地震断層 / 熊本県西原村 / 正断層 / 熊本県阿蘇市 / 阿蘇カルデラ |
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| Outline of Final Research Achievements |
In this study, we conducted paleoseismic trenching surveys at two sites where small displacements appeared along faults far from the principal fault (Futagawa fault) that caused the 2016 Kumamoto earthquake. We investigated whether the faults with small displacements had moved at the same time as the Futagawa fault in the past. The results were consistent with the paleoseismic history of the Futagawa fault at both sites. This means that a low-slip-rate active fault can be triggered with adjacent high-slip-rate active faults like the Futagawa fault. From these facts, we are able to demonstrate a new style of activity of low-slip-rate active faults.
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| Academic Significance and Societal Importance of the Research Achievements |
低活動度の活断層は，単独では長い周期で地震を発生させ，地表に変位を生じさせると考えられ，その地震や変位に対するリスクは低く見積もられがちであった．しかし，本研究では，低活動度活断層の中でも周囲に高活動度の活断層がある場合には，その高活動度活断層の活動に誘発されて低活動度活断層が変位することを示した．このことは，低活動度活断層の多様性を示すとともに，従来の考えに比べて，高い頻度で地表に変位をもたらすことを意味する．今後，このような多様性を実証的な情報をも基に検証することで，より現実的な活断層による変位ハザードの評価に繋がることが期待される．
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Report
(5 results)
Research Products
(12 results)
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[Presentation] Paleoseismic trenching on the subsidiary surface ruptures associated with the mainshock of the 2016 Kumamoto earthquake sequence2020
Author(s)
Ishimura, D., Takahashi, N., Tsutsumi, H., Kumahara, Y., Toda, S. and Ichihara, T.
Organizer
Hokudan 2020 International Symposium on Active Faulting
Related Report
Int'l Joint Research / Invited
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