パークフィールドにあるサンアンドレアス断層の断層強度変化のリモートトリガー
Taka'aki Taira1, Paul G Silver, Fenglin Niu
1Department of Terrestrial Magnetism, Carnegie Institution of Washington, District of Columbia 20015, USA. taira@dtm.ciw.edu
Nature
|October 2, 2009
まとめ
科学者たちは,サンアンドレアス断層の地震データを用いて断層の強さを監視する新しい方法を開発しました. 2004年のスマトラ・アンダマン地震のような大規模な地震は,地球規模で断層の強さを遠隔操作で変化させ,地震活動をさらに引き起こす可能性があります.
科学分野:
- 地震学 地震学とは
- 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
背景:
- 断層の強さは,地震の発生可能性と発生を把握するために重要です.
- 断層の強さの変化を in situ で監視することは,大きな課題でした.
- 地震性のリモートトリガーは,外部の影響が故障行動に及ぼす可能性を示唆しています.
研究 の 目的:
- 断層強度における時間的な変化をモニタリングするための新しい方法を提示する.
- 地元の断層の強さに大きな遠隔地震が及ぼす影響を調査する.
- 断層強度の乱れがもたらす世界的な影響を調査する.
主な方法:
- サンアンドレアス断層のパークフィールド地域から約20年間の観測データ (1987年 - 2008年) の分析.
- 流体移動の兆候である地震散乱器の特性における時間的変動の識別.
- 断層の強さの変動を推論するために,繰り返される地震のシーケンスにおける体系的な変化の検討.
主要な成果:
- 1992年のLanders地震と2004年のSumatra-Andaman地震に関連した,おそらく遠隔断層の強度の変化の2つの事例が特定されました.
- 観測された変化には,地震散布器の変動と重複する地震の特徴が含まれています.
- 1992年のLanders地震は,断層の強さを低下させ,その後パークフィールドで発生した地震を誘発した可能性がある.
結論:
- 大規模な地震は,断層の強度に大きな長期的な変化を引き起こす可能性があります.
- 流体移動によって引き起こされる可能性があるこれらの変化は,地震性に影響を与える可能性があります.
- この調査結果は,大規模な地震が断層システムに世界的な影響を及ぼし,クラスター地震を引き起こす可能性があることを示唆しています.
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