実験室での実験で決定された東北・オキ大震災における低コセイズム切断ストレス
Kohtaro Ujiie1, Hanae Tanaka, Tsubasa Saito
1Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.
Science (New York, N.Y.)
|December 7, 2013
まとめ
2011年の東北大震災は,以前はありえないと考えられていた大きな浅い滑りを示した. 実験により,豊富な粘土と熱圧圧が,この巨大な断層の動きと,その後の津波を説明することを明らかにした.
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:
- 浅いプレート境界の推力は,大きなコセイズミックスリップを生むとは予想されませんでした.
- 2011年の東北大震災 (Mw=9.0) は,日本溝の近くで~50メートルの移動を引き起こし,壊滅的な津波を引き起こしました.
研究 の 目的:
- 東北大震災で観測された例外的に大きな断層の動きの背後にあるメカニズムを調査します.
- プレート境界のスラストに重大な浅い滑りをもたらす要因を決定する.
主な方法:
- 高速 (1.3 m/s) の摩擦実験を行った.
- 東北大震災の原因となったプレート境界の推力から採取した岩石サンプルを使用した.
主要な成果:
- 摩擦実験の際に少量のストレスの低下が観察されました.
- 非常に低いピークと安定状態の切断ストレスを測定しました.
- 弱い粘土 (スメクタイト) と熱圧縮効果の豊富な存在が確認されました.
結論:
- 豊富なスムクタイト粘土と熱圧圧は,断層の滑り方を容易にします.
- これらの要因は,2011年の東北大震災時の大きな浅い滑り方を説明する.
- 浅い推力断層での大規模な移動のためのメカニズムを提供します.
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