Seafloor Geodetic Observations to Reveal Co- and Post-Seismic Slip Distributions of the 2011 Tohoku-Oki Earthquake
Seafloor Geodetic Observations to Reveal Co- and Post-Seismic Slip Distributions of the 2011 Tohoku-Oki Earthquake
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海底大地测量观测揭示 2011 年东北冲地震的震中和震后滑移分布
DOI：
10.1109/oceanskobe.2018.8559370
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
and N. Uchida
中科院分区：
文献类型：
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作者：
Tomita;F.;Y. Ohta;T. Iinuma;R. Hino;M. Kido;and N. Uchida
2011年3月11日发生的东北冲地震（M9.0）。许多研究基于陆地地震学和大地测量数据以及海底大地测量数据来调查地震在板块界面上的同震滑动分布。然而，由于在主震前安装的海底台站集中在宫城县外地区，因此，沿沿着与日本海沟平行的方向，浅板块界面上非常大的滑动区域的空间范围没有得到很好的限制。主震发生后，全球导航卫星系统地面观测站和海底观测站网络（包括2011年东北冲地震后安装的20个新海底观测站）检测到了大的震后变形。近海地区的震后位移速率场表明，弹性地壳下软流圈层的粘弹性松弛是震后变形的主要原因，而不是板块界面的后滑。由于同震滑移引起的应力扰动激发了粘弹性松弛，震后位移速率提供了有关同震滑移的信息。因此，它是可能的约束同震滑移分布的浅板界面附近的日本海沟，地震后的位移的基础上，通过应用绿色的功能，其中包括粘弹性位移的演变。我们同时反演了同震和震后位移数据，以估计2011年东北冲地震的同震和震后滑动分布，其空间分辨率优于基于弹性绿色函数的模型。结果表明，浅部同震破裂的最大延伸范围为日本海沟附近的37.0°N ~ 39.2°N。由于引入了新建立的全球导航卫星系统声学观测网络，与以前的研究相比，后滑分布也受到了很好的限制。
The 2011 Tohoku-Oki earthquake (M9.0) occurred on March 11, 2011. Many studies have investigated the co-seismic slip distribution of the earthquake on the plate interface based on terrestrial seismological and geodetic data and seafloor geodetic data. However, since seafloor stations installed before the main shock were concentrated in the off Miyagi Prefecture area, the spatial extent of the area of very large slip on the shallow plate interface was not well constrained along the direction parallel to the Japan Trench. After the main shock, large post-seismic deformations were detected by the terrestrial Global Navigation Satellite System (GNSS) observation stations and the seafloor station network, which includes 20 new seafloor stations installed after the 2011 Tohoku-Oki earthquake. The post-seismic displacement rate field in the offshore area revealed that the viscoelastic relaxation in the asthenospheric layer beneath the earth's elastic crust is the main cause of the post-seismic deformation not the afterslip on the plate interface. Since stress perturbation due to the co-seismic slip excited the viscoelastic relaxation, the post-seismic displacement rates provide information about the co-seismic slip. Therefore, it is possible to constrain the co-seismic slip distribution on the shallow plate interface near the Japan Trench, based on the post-seismic displacements by applying Green's function, which includes viscoelastic displacement evolution. We simultaneously inverted co- and post-seismic displacement data to estimate the co- and post-seismic slip distributions of the 2011 Tohoku-Oki earthquake with better spatial resolution than models based on the elastic Green's function. The result indicates that the shallow co-seismic rupture extended maximally from 37.0°N to 39.2°N near the Japan Trench. Afterslip distribution was also well constrained in comparison to previous studies because of the introduction of the newly established GNSS-Acoustic observation network.