刘渊, 薛梅. 2021: 利用DONET海底观测网研究日本南海海域俯冲带地震波各向异性. 地震学报, 43(1): 73-83. DOI: 10.11939/jass.20200087
引用本文: 刘渊, 薛梅. 2021: 利用DONET海底观测网研究日本南海海域俯冲带地震波各向异性. 地震学报, 43(1): 73-83. DOI: 10.11939/jass.20200087
Liu Yuan, Xue Mei. 2021: Seismic anisotropy within the Nankai area,Japan,using DONET seafloor observation network. Acta Seismologica Sinica, 43(1): 73-83. DOI: 10.11939/jass.20200087
Citation: Liu Yuan, Xue Mei. 2021: Seismic anisotropy within the Nankai area,Japan,using DONET seafloor observation network. Acta Seismologica Sinica, 43(1): 73-83. DOI: 10.11939/jass.20200087

利用DONET海底观测网研究日本南海海域俯冲带地震波各向异性

Seismic anisotropy within the Nankai area,Japan,using DONET seafloor observation network

  • 摘要: 基于DONET海底观测网的直达S波地震记录,采用波形旋转互相关方法和最小特征值最小化方法求得了日本南海海域俯冲带横波分裂快轴方向和分裂时间,获得了该俯冲带地震波的各向异性结果。结果显示:该俯冲带地震波的各向异性快轴方向基本平行于南海海槽走向,分裂时间为0.1—0.96 s。这表明:日本南海海域俯冲带各向异性来源于太平洋俯冲板块上覆地幔楔和菲律宾海俯冲板块;地幔楔各向异性产生于二维地幔楔拐角流所导致的各向异性矿物晶体的定向排列;菲律宾海俯冲板块的各向异性则产生于板块扩张时期形成的“化石各向异性”和俯冲过程中板块挠曲产生的断层;日本南海海域俯冲带大范围变化的分裂时间反映了该地区各向异性介质的强度和(或)厚度的不均匀性。

     

    Abstract: Based on the direct S-wave seismic records of the DONET seafloor observation network, this paper obtains the orientation of shear wave splitting fast axis and splitting time of Naikai area of Japan by using the cross-correlation method and the smallest eigenvalue minimization method. The results show the fast axis of the anisotropy in the subduction zone is sub-parallel to the strike of the Nankai trough, and the splitting time ranges from 0.1 s to 0.96 s. This indicates that the anisotropy of the Nankai subduction zone originates from the mantle wedge which overlies the subducted Pacific Plate and the subducted Philippine Sea slab. The anisotropy of the mantle wedge is caused by the existence of two-dimensional corner flow that causes the anisotropic mineral crystals to be oriented along the direction perpendicular to the trench. The anisotropy of the subducted Philippine Sea slab is caused by the “fossil anisotropy” and the faults related to the plate bending during the subduction. The widely varying splitting times reflect the inhomogeneous strength and/or thickness of the anisotropic structure beneath the area.

     

/

返回文章
返回