Seismic anisotropy of the Northeastern Tibetan Plateau from shear wave splitting analysis
Seismic anisotropy of the Northeastern Tibetan Plateau from shear wave splitting analysis
复制标题
青藏高原东北部地震各向异性的剪切波分裂分析
DOI：
10.1016/j.epsl.2011.01.026
复制
发表时间：
2011-04-01
影响因子：
5.3
通讯作者：
Zhang, Ruiqing
中科院分区：
文献类型：
--
作者：
Li, Yonghua;Wu, Qingju;Zhang, Ruiqing
在西宁及其邻近地区，各向异性表现出强烈的劈裂参数方位依赖性，可以用两个各向异性层来模拟。上层快速方向位于n75 ~ 95°E范围内，与GPS确定的地表运动方向一致，可能与中下地壳流动有关。低层的快速方向在N105-125°E范围内，与只需要单层的西部和北部观测到的方向相似。这些NWW-SEE或nww - se快速特征可能与印度-欧亚大陆碰撞引起的造山运动有关，或者与欧亚大陆的绝对运动有关的软流圈流动有关。将所提出的模型所期望的各向异性模式与我们的横波分裂观测结果进行比较表明，没有一个独特的地球动力学模型可以调和这样一个复杂地区的所有分裂测量结果。(C) 2011 Elsevier B.V.版权所有
We present shear wave splitting results obtained from the analysis of teleseismic SKS, SKKS and PKS phases recorded by 70 permanent seismographic stations located in the Northeastern Tibetan Plateau. We identify a contrast in the splitting pattern complexity beneath different parts of NE Tibet In the western and northern part, anisotropy observations are well explained by a single layer of anisotropy with a fast anisotropic direction trending NWW-SEE or NW-SE. In Xining and its adjacent area, the anisotropy shows strong azimuthal dependence of splitting parameters that can be modeled by two anisotropic layers. The fast direction for the upper layer lies in the N75-95 degrees E range, which is consistent with the surface movement direction determined from GPS, and could be associated with middle to lower crustal flow. The fast direction in the lower layer is in the N105-125 degrees E range and similar to the direction observed in the western and northern part where only a single layer is required. These NWW-SEE or NW-SE fast feature could be related to the current orogenesis induced from the India-Eurasia collision, or flow in the asthenosphere related to the absolute motion of Eurasia. Comparison between the anisotropy patterns expected from proposed models with our shear wave splitting observation suggests that no unique geodynamic model can reconcile all splitting measurements for such a complex region. (C) 2011 Elsevier B.V. All rights reserved.