誘発された地震性. 流体注入による非地震性滑りによって引き起こされる地震性

Yves Guglielmi¹, Frédéric Cappa², Jean-Philippe Avouac³

¹Centre de Recherche et d'Enseignement de Géosciences de l'Environnement (UMR7330), University of Aix-Marseille, CNRS, IRD, 13545 Aix-en-Provence, France. guglielmi@cerege.fr.

Science (New York, N.Y.)

|June 13, 2015

まとめ

液体注入は地震を引き起こす可能性がありますが,そのメカニズムは不明です. この研究は,流体注入が主にゆっくりと無地震的な断層滑りを引き起こし,間接的にマイクロ地震につながることを示しています.

科学分野:

地質物理学地質物理学とは地質物理学です.
地震科学地震科学地震科学
流体力学流体力学とは

背景:

地熱エネルギーや炭化水素抽出などの液体注入は,地震を誘発することが知られている.
液体注入と地震発生を結びつける正確なメカニズムは完全に理解されていないため,地震リスクの評価が制限されています.

研究の目的:

自然断層に流体注入によって誘発される断層滑りと地震性を直接測定するために.
流体圧,断層の振る舞い,およびマイクロ地震発生の関係を解明する.

主な方法:

自然断層への流体注入を制御する際の断層滑りと地震性の直接測定.
微小からナノメートルのスケールでの透過性変化と滑り率の監視.
圧力下での断層摩擦法則と滑り方に関する分析.

主要な成果:

観測された高度に膨張し,ゆっくりとアセイミックスリップ (約. 4μm/s) と一致し,透過性が20倍に増加した.
より速い滑りへの移行 (約. 10μm/s) で,膨張率が低下し,マイクロ地震が発生する.
流体圧力ゾーン内では,速度強化摩擦法 (μ = 0.67 + 0.045ln(v/v0)) に従って無地震滑行が優位であった.

結論:

液体注入は,主に自然断層の無地震性滑り方を促進する.
微小地震は,流体圧力と断層特性によって媒介される無地震のクリープの間接的な結果である.
アセイミックスリップの理解は,流体注入活動に関連する地震リスクの評価に不可欠です.

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