東太平洋の上昇変形断層のフォームロックシーケンスと短期的な地震予測能力
Jeffrey J McGuire1, Margaret S Boettcher, Thomas H Jordan
1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1541, USA. jmcguire@whoi.edu
Nature
|March 26, 2005
まとめ
東太平洋の上昇変形断層は,頻繁な前震と少数の余震でユニークな地震行動を示しています. このパターンは,スロースリップトランジエントが地震を引き起こす可能性を示唆し,変形断層の地震予測に役立ちます.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- プレート・テクトニクス (プレート・テクトニクス)
背景:
- 東太平洋の上昇変換断層は,高滑り率 (>10cm/yr),主に無地震滑り,そして適度な最大震度 (~6.5) を特徴としています.
- 大陸のストライクスリップ断層は,海洋の変換断層と比較して,通常,異なる前震対後震比を示します.
研究 の 目的:
- イースト・パシフィック・ライズ・トランスフォーム・フォールの地震特性を調査する.
- 地震性のパターンを大陸のストライクスリップ断層と比較するために.
- 地震誘発モデルと予測可能性に関する観測パターンの影響を調査する.
主な方法:
- 国立海洋大気管理局 (NOAA) からの水音波配列記録の分析.
- 予震と余震の比率の比較分析.
- 観測された地震性に基づく地震誘発モデルの評価.
主要な成果:
- 東太平洋の上昇変換断層は,余震の数が少なく,前震率が高いことを示している.
- 観測された前震と余震の比率は,従来の地震誘発モデルに異議を唱える.
- フロームラックシーケンスにより,特定の時空窓内での地震 (M≥5.4) の予後予測が可能となり,高確率の得点が得られた.
結論:
- 東太平洋上昇におけるトランスフォーム断層の地震性は,大陸断層とは異なる.
- 地震を誘発するスロースリップトランジエントを含むモデルは,観測されたパターンと予測可能性を説明します.
- この研究は,アセイミック・プレート・モーション・アコモダーションのメカニズムと,変形断層における地震発生の仕組みの洞察を提供します.
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