安定した爬行断層は,ダイナミックな弱体化の結果として破壊的になる可能性があります
1Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, 236-0001, Japan. hnoda@jamstec.go.jp
Nature
|January 11, 2013
まとめ
地震断層は,ゆっくりと転がり,突然の破裂の両方を示し,以前の仮定に異議を唱えます. 新しいモデルでは,シアヒートによるシールヒートによって,滑りやすい断層に不安定な滑り込みが起こり,地震リスクの評価に影響を及ぼすことを説明しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- 地震学 地震学とは
背景:
- 地球の地殻の断層は,ゆっくりと滑り落ちたり,急激に,地震を起こす破裂を介して,構造板の動きに対応します.
- 断層セグメントは,しばしば摩擦のタイプによって分類されます:速度強化 (安定した滑り) または速度弱化 (スティックスリップ).
- 2011年の東北大震災の大きな滑り込みは,この仮定に異議を唱えた.
研究 の 目的:
- 安定したクリープとコセイズミック弱化を統合したモデルを断層行動に提案する.
- 通常は這い回るセグメントで不安定な滑り方がどのように起こるかを説明するために.
- 東北大震災と千葉大震災の複雑な観測結果を再現し,説明する.
主な方法:
- 低滑り率での速度強化摩擦と,ポア流体切断加熱によるコセイズミック弱化を組み合わせたモデルを開発した.
- モデルパラメータ化のために1999年のチチ地震の断層地帯からの実験室測定を用いた.
- 長期の滑り方をシミュレートするために,すべての波効果を組み込んだ新しい数学的アプローチを採用しました.
主要な成果:
- このモデルは,故障行動の見かけに矛盾する観測を成功裏に再現します.
- それは,低滑り地域からの高周波放射線と,爬行するセグメントの大きな滑り方を説明します.
- このモデルは,東北沖破裂の複雑さと,歴史的地震性のパターンを説明しています.
結論:
- 地震の破裂は,以前は障壁と見なされていた,ひっくり返る断層の断層を通って拡散することができます.
- この発見は,多くの地域における地震リスクの評価を再評価することを必要としています.
- 提案されたモデルは,さまざまな故障スリップ行動に対する統一された説明を提供します.
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