| Project/Area Number |
19K04046
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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 |
Otsubo Makoto 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, 研究グループ長 (70443174)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2021: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2019: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
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| Keywords | 南海トラフ / 地震 / 鉱物脈 / 亀裂 / 流体移動 / 流体圧 / スロー地震 / 海溝型地震 / 流体 / 応力 / 断層 / クラック / 石英 / 間隙水圧 / 沈み込み帯 |
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| Outline of Research at the Start |
本研究は，①海溝型巨大地震発生前後での断層周辺における間隙水圧の時間変化と②地震発生後のプレート境界に沿った断層強度の回復量を推定し，南海トラフ地震評価のための基礎資料を提供する．
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| Outline of Final Research Achievements |
Using the poroelastic model of quartz veins filling extensional fractures in the Shimanto Belt, the formation of extensional fractures releases at most a few percent of the total pore pressure at depths of up to 8 km, indicating that the pore pressure near giant branch faults was close to lithostatic pressure throughout the entire earthquake cycle. The pore water pressure near the giant bifurcation fault was close to the static rock pressure throughout the entire earthquake cycle. A negative correlation was found between the amount of fluid pressure that exceeded the minimum principal stress and the spacing of mineral veins.
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| Academic Significance and Societal Importance of the Research Achievements |
研究成果は地震後の伸張性亀裂による間隙流体圧の低下が巨大分岐断層の断層強度を増加させるのにほとんど寄与せず，つまり，断層面付近は間隙流体圧が高い状態が維持されている可能性を示す．また，鉱物脈同士の間隔はスロー地震の発生サイクル内での間隙流体圧の過剰分の時間変化の結果である可能性があり，間隙流体圧の過剰分がスロー地震のサイズを規定する可能性がある．
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