Pn tomographic velocity and anisotropy beneath the Tibetan Plateau and the adjacent regions
Pn tomographic velocity and anisotropy beneath the Tibetan Plateau and the adjacent regions
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DOI：
10.5047/eps.2011.07.013
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
Yan Lü;S. Ni;B. Liu;Youshun Sun
中科院分区：
文献类型：
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作者：
Yan Lü;S. Ni;B. Liu;Youshun Sun
该研究分析了来自国际地震中心（ISC）和中国地震数据中心的105385个Pn相位读数。研究区的平均Pn速度约为8.15 km/s，速度扰动高达3-4%。在印度板块下、塔里木盆地和四川盆地内存在高Pn速度，在兴都库什山脉下、缅甸及其邻近地区存在低Pn速度，特别是在印度河-雅鲁藏布河缝合带以北地区存在低Pn速度。在碰撞区，印度板块的高Pn速度异常在东西方向上是不连续的，表明印度板块可能是分段俯冲的。Pn速度分布被用来验证先前研究中提出的印度板块俯冲机制。此外，Pn各向异性与Pn速度同时得到。在板块碰撞区，快速Pn各向异性方向平行于碰撞边缘方向。我们验证了这些区域内Pn各向异性的存在，并讨论了各向异性与构造和板块运动的关系。
We present a tomographic velocity and anisotropy model of the uppermost mantle beneath the Tibetan Plateau and the adjacent regions. The investigation analyzed 105,385 Pn phase readings from the International Seismological Centre (ISC) and the China Earthquake Data Center. The average Pn velocity under the study area is approximately 8.15 km/s, with velocity perturbations up to 3–4%. We find high Pn velocities under the Indian Plate and in the Tarim and Sichuan basins, low Pn velocities under the Hindu Kush and in Myanmar and the adjacent region, and especially low Pn velocities under the area north of the Indus-Yarlung Zangbo suture. The high Pn velocity anomalies of the Indian Plate are discontinuous at the collision region in the east-west direction, indicating that the Indian Plate probably subducts in a piecewise manner. Distributions of Pn velocities are used to validate mechanisms for the subduction of the Indian Plate presented in previous studies. In addition, Pn anisotropy is obtained simultaneously with Pn velocity. At plate collision zones, the fast Pn anisotropy direction is parallel to the direction of the collision edge. We validate the existence of Pn anisotropy under these regions and discuss the relationship of anisotropy with tectonic structure and plate movement.