プレッシャー過大で沈殿した海洋地殻とメガトラストの断層密封の地震的証拠
Pascal Audet1, Michael G Bostock, Nikolas I Christensen
1Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. paudet@berkeley.edu
Nature
|January 6, 2009
まとめ
海洋地殻を潜水している水は,低透性のメガスストを示しています. 流体の圧力の変化が,高透度インターフェイスへの移行を促し,潜流ゾーンのダイナミクスと地震発生に影響を与えます.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- ミネラル物理学 ミネラル物理学
背景:
- 水と水性ミネラルは,潜水地帯の地力学にとって不可欠であり,プレート境界の弱まりと滑りに影響を与えます.
- 地震異常は前弓マントルの (蛇形化) に水があることを明らかにしますが,潜水板にその存在はあまり理解されていません.
研究 の 目的:
- 沈下する海洋地殻内の水の存在と状態を調査する.
- プレートインターフェースの浸透性および潜水ゾーンプロセスに対する水の存在の影響を理解する.
主な方法:
- 変換されたテレシーミック波を利用して,地震波の行動を分析した.
- 沈下した海殻の中で異常に高いポアソンの比率を解釈した.
主要な成果:
- カスカディアの海底地殻でポアソンの比率が上昇したことが観察され,これは,リソスタティックに近い孔圧で流動水が浸透していることを示しています.
- 海洋地殻の頂部に強い負の速度コントラストを特定し,低透過性のメガスストを示唆しました.
- 提案された水力断裂は,エコロギティゼーションとサーペンティニゼーションによって駆動され,高透過性のインターフェースダウンディップへの移行を説明します.
結論:
- 潜水した地殻に浸透した液体の水は,低透性のメガスラストシールを暗示しています.
- プレート界面の浸透性の移行は,体積の変化と水力破裂によるものです.
- この発見は,地震発生,潜流ゾーン構造,エピソード的な震動と滑りメカニズムを理解する上で重要な意味を持つ.
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