Along-arc heterogeneous rheology inferred from post-seismic deformation of the 2011 Tohoku-oki earthquake
Along-arc heterogeneous rheology inferred from post-seismic deformation of the 2011 Tohoku-oki earthquake
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根据 2011 年东北大地震震后形变推断的沿弧非均质流变学
DOI：
10.1093/gji/ggac063
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发表时间：
2022
影响因子：
2.8
通讯作者：
Iinuma Takeshi
中科院分区：
文献类型：
--
作者：
Dhar Sambuddha;Muto Jun;Ito Yoshiaki;Miura Satoshi;Moore James D P;Ohta Yusaku;Iinuma Takeshi
2011年日本东北冲地震引起的巨大应力扰动，在调节震后变形方面，日本前弧起着至关重要的作用。日本各地密集的大地测量观测揭示了俯冲板块界面上的后滑和地幔楔内的粘性变形之间的耦合作用，详细的数值模型可以为弧前流变学提供更深入的见解。最近的研究表明，东北俯冲带的弧前地幔中存在一个停滞的部分，在这里，我们调查了日本各地的地幔楔（冷鼻）的停滞部分的相关沿弧变化。我们利用一个新部署的大地测量网络沿着一个走廊在福岛-新潟地区和比较的表面变形模式的宫城-山形走廊靠近主破裂区。我们提出了一个三维流变模型，使用实验室推导的本构关系来模拟大地测量观测，包括位移场及其时间序列。我们的研究结果表明，沿弧前地幔流变学的不均匀性，特别是，我们发现一个狭窄的冷鼻在宫城地区和一个更广泛的福岛弧前。弧前变化的大地测量推断是一致的沿弧的空间异质性的截止深度为浅地震，以及比较测量各自的地热梯度之间的宫城和福岛地区。
The Japan forearc plays a crucial role in modulating the post-seismic deformation in response to the enormous stress perturbation induced by the 2011 Tohoku-oki earthquake. Dense geodetic observations across Japan have revealed coupled interactions between afterslip on the subducting plate interface and viscous deformation within the mantle wedge, and detailed numerical models can provide further profound insights into the forearc rheology. Recent studies have revealed the presence of a stagnant section in the forearc mantle of the Tohoku subduction zone, and here we investigate the associated along-arc variation of the stagnant part of the mantle wedge (cold nose) across Japan. We utilize a newly deployed geodetic network along a corridor in the Fukushima–Niigata region and compare the surface deformation pattern to that of the Miyagi–Yamagata corridor close to the main rupture area. We present a 3-D rheological model using laboratory-derived constitutive laws to simulate the geodetic observations including displacement fields and their time-series. Our results suggest along-arc heterogeneity in the forearc mantle rheology; specifically, we find a narrower cold nose in the Miyagi region and a wider one in the Fukushima forearc. The geodetic inferences on the forearc variation are consistent with along-arc spatial heterogeneity in the cut-off depth for shallow earthquakes as well as comparative measurements of the respective geothermal gradients between the Miyagi and Fukushima regions.