カスカディアの北のマージンに沿った地震による震動の広大な深さ分布
Honn Kao1, Shao-Ju Shan, Herb Dragert
1Geological Survey of Canada, Pacific Geoscience Centre, 9860 West Saanich Road, Sidney, British Columbia V8L 1B9, Canada. hkao@nrcan.gc.ca
Nature
|August 12, 2005
まとめ
カスカディア・サブドクション・ゾーンの震動は,40kmの深さ範囲でエピソード的に発生します. これらの地震現象は,流体の関与を示唆し,プレート界面に沿って一時的な滑り,または拡散されたエピソード的滑りを示唆する可能性があります.
科学分野:
- 地球科学 地球科学 地球科学
- 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.
背景:
- カスカディアの潜水地帯は,そのロックされたオフショアプレートインターフェースのために,大きな地震 (M (w) = 9) を発生させる能力があります.
- 震動のような地震シグネチャーを持つエピソード的な表面の移位は,長期の変形に逆らって,およそ14ヶ月ごとに発生します.
研究 の 目的:
- カスカディア・サブデュークション・ゾーンにおける地震のような地震の空間的分布と特性を調査する.
- これらのエピソード的な地震現象の根本的なメカニズムと影響を理解する.
主な方法:
- プレートインターフェースの振る舞いを推論するために,地質学的データの分析.
- 震動の分布と深さを特徴付けるための地震データ分析.
- 震動の位置と地震反射器とプレートインターフェースの相関.
主要な成果:
- 地震は,狭い水平帯域内で40kmを超える深さ範囲に分布しています.
- 多くの震動は,プレート界面上の強力な地震反射器の近くで発生し,局所的な地震が欠けている地域です.
- 地震の発生過程は,流体に関連しているようです.
結論:
- 観測された震動の深さ範囲は,より深いカスカディアプレートインターフェースの一時的な滑りによって誘発されたストレスフィールドの変動との関連を示唆しています.
- また,今回の発見は,エピソード性滑り方が,これまで考えられていたよりも拡散していることを示唆している.
- これらの震源を理解することは,カスカディア地域における地震リスクの評価に不可欠です.
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