フアン・デ・フカ山脊の海底の広がりエピソードに対する水文学的反応
Earl Davis1, Keir Becker, Robert Dziak
1Pacific Geoscience Centre, Geological Survey of Canada, Sidney, British Columbia V8L 4B2, Canada. edavis@nrcan.gc.ca
Nature
|July 16, 2004
まとめ
地震の群れの間に海底が広がり,フアン・デ・フカ山脈の液圧が驚くほど低下した. これは,地殻が膨張し,おそらくマグマではなく水で満たされていることを示唆しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 海洋学 海洋学とは
- 水文地質学 水文地質学は,水文地質学である.
背景:
- 海底熱水系は通常,地震およびマグマ現象に反応し,活動が増加します.
- 以前の観測は,熱水放出,温度,微生物の活性におけるポジティブな変化に焦点を当てていた.
研究 の 目的:
- 沈殿物で封じ込められた火性地殻の海底の広がりに対する水文学的反応を調査する.
- 地震群の発生と発生後のミドルバレー・リフトの圧力変化を分析する.
主な方法:
- 1991年に設立された掘削穴シールと水文観測所を利用した.
- 熱水活動地域における安定状態の圧力および温度状態を監視する.
- 共同地震圧力トランジエントとスエーム後の水文学的振る舞いを分析した.
主要な成果:
- 地震群の発生中および発生後,形成液圧の有意な負の一時的な変化が観察されました.
- 同地震圧力反応の大きさは,地震からの予想される弾性ストレンスと一致しています.
- 長期にわたる負圧トランジントは,上部熱地殻の共地震膨張を示唆している.
結論:
- この地域での海底の広がりは,マグマの侵入ではなく地殻の膨張を誘発した.
- 広がりによって作られた空白は,おそらく水で満たされ,観測された圧力低下につながった.
- 地震後の水柱の水熱活動の増加は検出されなかった.
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