2011年の東北大震災後の粘弾性緩解の発生率について
Tianhaozhe Sun1, Kelin Wang2, Takeshi Iinuma3
1School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8P 5C2, Canada.
Nature
|September 19, 2014
まとめ
大規模な地震の後の地震後の変形は,主に粘弾性緩解によって引き起こされ,滑り直後の変形だけではありません. 新しい海底GPSデータは,短期的な動きにおけるこの支配的な役割を明らかにし,断層の行動と地球に関する以前の仮定に異議を唱える.
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
- テキトノフィジックスの物理学です.
背景:
- サブダクション地震の後の地震後の変形は複雑で,粘着弾性リラックスとアフタースリップの影響を受けます.
- 以前の研究では,しばしば,アフタースリップが短期的な変形を主導し,粘性弾性性が長期的にしか役割を果たさないと仮定していました.
- この仮説を従来の地質データで検証するのは,大変な課題でした.
研究 の 目的:
- 東北大震災後の短期的な地震後の変形を引き起こす支配的なメカニズムを調査する.
- 主要な潜水イベントの直後のアフタースリップに対する粘着弾性リラクゼーションの役割を評価する.
- 新しい観測データに基づいて,故障行動モデルを再評価する.
主な方法:
- 東北大震災直後に取得された新しい海底グローバルポジショニングシステム (GPS) の観測結果の分析.
- 暫定的な粘弾性マントルのレオロギーをシミュレートする数値モデルの開発と応用.
- 観測された変形パターンのモデル予測との比較.
主要な成果:
- 短期的な地震後の変形における粘弾性リラクゼーションの支配的な役割に対する明確な証拠.
- 溝の領域の陸面への急速な動きが観測され,陸面での海面への動きと対照的である.
- 陸への動きは,非対称な地震の破裂によるストレス緩和の結果であることを実証した.
結論:
- 粘弾性緩和は,以前の仮定に反して,短期的な地震後の変形の重要な要因です.
- この発見は,下落のアフタースリップを過大評価し,上昇のアフタースリップを過小評価したモデルを改訂することを必要としています.
- 断層摩擦を理解するには,変形パターンに対する粘着弾性の重要な影響を考慮する必要があります.
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