Shear-wave splitting in the southeast of Cathaysia block, South China
Shear-wave splitting in the southeast of Cathaysia block, South China
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DOI：
10.1007/s10950-008-9126-y
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发表时间：
2009-04
影响因子：
1.6
通讯作者：
Yuan Gao;Jing Wu;Jinan Cai;Yu-tao Shi;Shu-Jeng Lin;Ting Bao;Zu-ning Li
中科院分区：
文献类型：
--
作者：
Yuan Gao;Jing Wu;Jinan Cai;Yu-tao Shi;Shu-Jeng Lin;Ting Bao;Zu-ning Li
本研究的重点是华夏地块（SECB）东南部的中国福井省。本文利用福建地震台网提供的资料，研究了地壳的地震各向异性。通过系统的分析和适当的软件包，我们检查剪切波分裂从1999年1月至2003年12月期间在10个FJSN站记录的数据。结果表明，快波平均偏振度为N109.4° E ± 42.6°，对应于试验区的水平主压应力，慢波平均归一化时延为2.5 ± 1.5ms/km。东南板块东部各台站的优势极化方向为N-W向，这与区域水平主压应力有关，也与断裂走向有关。相反，在SECB西部的两个台站的优势极化是在N-E方向。这种极化方向与水平主压应力方向不一致，但与近断层走向一致，反映了局部构造的影响和应力场的变化。结果表明，当台站位于活动断层上时，其优势极化方向与断层走向平行。在海岸线附近的少数台站，某些极化显示出一定程度的散射，这可能是由交叉断层和不规则地形造成的。最后，时间延迟的空间分布在地震活动相对较大的海岸附近表现出强烈的横向变化，因此各向异性的大小似乎与地震活动最活跃的地区一致。
This study is focused on Fujing Province in China, southeast of Cathaysia block (SECB). The present work benefits from the data provided by the Fujian Seismic Network (FJSN) to study the seismic anisotropy in the crust. By means of a systematic analysis and adequate software package, we examine shear-wave splitting from data recorded at ten FJSN stations during the period January 1999 to December 2003. The results demonstrate that the average fast wave polarization is N109.4° E ± 42.6°, corresponding to the horizontal principal compressive stress in the test zone, and the average normalized slow wave time delay is 2.5 ± 1.5 ms/km. The predominant polarizations at stations in the eastern part of SECB are in the N–W direction, which suggests that they are related to the regional horizontal principal compressive stress and also to the strikes of faults. In contrast, the predominant polarizations at two stations in the western part of SECB are in the N–E direction. This polarization direction does not coincide with the direction of the horizontal principal compressive stress, but it follows the strikes of near faults, thus suggesting the influence of the local tectonics and a change in the stress field. The results prove that the predominant polarizations are parallel to the strikes of faults whenever the stations are on active faults. At a few stations near the coastal line, some polarizations show a certain amount of scatter which may be caused by crossing faults and irregular topography. Finally, the spatial distribution of time delays depicts strong lateral variations near the coast just where the seismic activity is comparatively bigger, so that the magnitude of anisotropy seems to be consistent with the most seismically active area.