School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada V8P 5C2.
Pacific Geoscience Centre, Geological Survey of Canada, Natural Resources Canada, 9860 West Saanich Road, Sidney, British Columbia, Canada V8L 4B2.
Nat Commun. 2017 Jan 11;8:14044. doi: 10.1038/ncomms14044.
During the 2011 magnitude 9 Tohoku-oki earthquake, very large slip occurred on the shallowest part of the subduction megathrust. Quantitative information on the shallow slip is of critical importance to distinguishing between different rupture mechanics and understanding the generation of the ensuing devastating tsunami. However, the magnitude and distribution of the shallow slip are essentially unknown due primarily to the lack of near-trench constraints, as demonstrated by a compilation of 45 rupture models derived from a large range of data sets. To quantify the shallow slip, here we model high-resolution bathymetry differences before and after the earthquake across the trench axis. The slip is determined to be about 62 m over the most near-trench 40 km of the fault with a gentle increase towards the trench. This slip distribution indicates that dramatic net weakening or strengthening of the shallow fault did not occur during the Tohoku-oki earthquake.
在 2011 年规模 9 级的东日本大地震中，俯冲带大逆冲断层的最浅部发生了非常大的滑动。浅层滑动的定量信息对区分不同的破裂机制和理解随后发生的毁灭性海啸至关重要。然而，由于缺乏近海沟的约束，浅层滑动的幅度和分布基本上是未知的，这一点可以从 45 个由大量数据集得出的破裂模型的汇编中得到证明。为了量化浅层滑动，我们在这里对地震前后沿海沟轴的高分辨率水深差异进行建模。结果表明，在最靠近海沟的 40 公里断层上，滑动约为 62 米，向海沟方向逐渐增加。这种滑动分布表明，在东日本大地震期间，浅部断层并没有发生显著的净弱化或强化。
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