2009年のサモア・トンガ大震災は,二重の地震を引き起こした.
Thorne Lay1, Charles J Ammon, Hiroo Kanamori
1Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064, USA. tlay@ucsc.edu
Nature
|August 21, 2010
まとめ
2009年の稀なトンガ地震の連続では,異常なプレート内イベントが,大規模なプレート内断層を誘発し,地震と津波の危険性を大幅に増加させた. この複雑な断裂は,壊滅的な津波波と広範囲にわたる余震を引き起こしました.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- テクトニクス (地質学) とは
背景:
- 大規模な地震は,通常,インタープレート破裂を含み,近隣のイントラプレート余震を引き起こす可能性があります.
- 通常のパターンは,インタープレートイベントがイントラプレート地震性を活性化することであり,その逆ではありません.
研究 の 目的:
- トンガの潜水地帯で発生した稀な地震の連続を分析するために,地板内地震が地板間断層を誘発した.
- この逆転した断裂パターンに関連した地震と津波の危険性を理解するために.
主な方法:
- 断層の断裂を区別するために地震波データを分析する.
- 2009年9月29日のトンガ地震のシーケンス,そのモメント・マグニチュードと断層メカニズムに関する調査.
主要な成果:
- マグニチュード8.1のイントラプレート地震は,数分以内に2つの主要なインタープレート (マグニチュード7.8のそれぞれ) を押し下ろしたサブイベントを誘発した.
- 結合した断層は,高さ12メートルの津波を発生させ,サモア,アメリカンサモア,トンガで死者を出した.
- 詳細な地震分析は,誘発推力故障を含む,異なる幾何学を持つ明確な断層を明らかにしました.
結論:
- 2009年のトンガ地震のシーケンスでは,典型的な地震誘発パターンの逆転が示されました.
- このイベントは地震と津波の危険性を大幅に拡大し,インタープレートとイントラプレート断層の複雑な相互作用を強調しました.
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