Rapid mantle flow with power-law creep explains deformation after the 2011 Tohoku mega-quake
Rapid mantle flow with power-law creep explains deformation after the 2011 Tohoku mega-quake
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DOI：
10.1038/s41467-019-08984-7
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发表时间：
2019-03-26
影响因子：
16.6
通讯作者：
Hori, Takane
中科院分区：
文献类型：
--
作者：
Agata, Ryoichiro;Barbot, Sylvain D.;Hori, Takane
大俯冲带地震后的形变瞬变被认为是软流圈地幔中的粘弹性流动和巨型逆冲推覆上的滑移相互作用的结果，两者都因同震应力突变而加速。在这里，我们表明，结合实验室固态蠕变和摩擦实验的洞察力，可以成功地解释2011年M-W 9.0东北冲地震后头几年地表形变的空间分布。软流圈位错蠕动导致的有效粘度的瞬时降低解释了海底大地测量揭示的特殊逆行位移，而巨型逆冲上的滑移加速解释了破裂区域外陆地和近海的地表位移。我们的结果表明，在软流圈中发生了一种快速的地幔流动，粘度暂时降低，以响应大的同震应力，这可能是由于地震后激活的幂定律蠕变所致。
The deformation transient following large subduction zone earthquakes is thought to originate from the interaction of viscoelastic flow in the asthenospheric mantle and slip on the megathrust that are both accelerated by the sudden coseismic stress change. Here, we show that combining insight from laboratory solid-state creep and friction experiments can successfully explain the spatial distribution of surface deformation in the first few years after the 2011 M-w 9.0 Tohoku-Oki earthquake. The transient reduction of effective viscosity resulting from dislocation creep in the asthenosphere explains the peculiar retrograde displacement revealed by seafloor geodesy, while the slip acceleration on the megathrust accounts for surface displacements on land and offshore outside the rupture area. Our results suggest that a rapid mantle flow takes place in the asthenosphere with temporarily decreased viscosity in response to large coseismic stress, presumably due to the activation of power-law creep during the post-earthquake period.