2011年の東北大震災の最大の避難地域におけるストレス状態
Weiren Lin1, Marianne Conin, J Casey Moore
1Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Japan. lin@jamstec.go.jp
まとめ
2011年の東北大震災は,日本の溝地域におけるストレスを大幅に軽減した. インサイトストレスの測定では,実質的な減少が確認され,活発な断層滑りと弱まりを示しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 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:
- 2011年の東北大震災 (マグニチュード9.0) は,日本海溝の近くで50メートル以上のコセシスミック・スリップを引き起こした.
- この極端な滑落は,地域的なストレス状態の有意な減少につながる可能性がある.
研究 の 目的:
- 地震後のストレス減少の仮説を検証する.
- イベントから約1年後のフロントプリズマのインサイトストレス状態を決定する.
- 地震前のストレス状態を推論するために.
主な方法:
- 水平的なストレスの方向と大きさを推定するために,掘削穴の突破口の分析.
- 統合海洋掘削プログラムによって掘削された掘削孔からのデータを活用する.
- 地震直前のストレス条件を,地震直後の測定とコセイズミックシフトデータに基づいて推論する.
主要な成果:
- 地震の際に,地上の水平ストレスの推定値は著しく減少した.
- 掘削穴の突破分析は,ストレスの方向と大きさの変化を明らかにした.
- 共同地震移転データによると,溝軸に向かって滑り込みが増加していることが示された.
結論:
- 観測されたストレス変化は,この地域でストレスが減少した仮説を裏付けている.
- 証拠によると,正面板のインターフェイスにアクティブな滑り込みがあることが示唆されています.
- 発見はコセイズミック断層の弱体化と,ほぼ完全なストレスの減少と一致しています.
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