Seismic array analysis and redetermination of depths of earthquakes in Tien-Shan: implications for strength of the crust and lithosphere
Seismic array analysis and redetermination of depths of earthquakes in Tien-Shan: implications for strength of the crust and lithosphere
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DOI：
10.1093/gji/ggu141
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发表时间：
2014-08
影响因子：
2.8
通讯作者：
A. Alinaghi;F. Krüger
中科院分区：
文献类型：
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作者：
A. Alinaghi;F. Krüger
自从有了宽带台阵资料以来，我们用已报道的天山地区下地壳和上地幔深度重新确定了中强地震和大地震的震源深度。全球地震台阵的地震记录已被用于确定深度相位和建立深度相位模型，以便准确估计震源深度。我们的研究结果表明，一半的据称深源地震确实起源于中地壳和下地壳地区的深度。准噶尔盆地天山北方前陆的一次异常事件位于上地幔64 km深处。这种板内大陆构造域的异常深震都发生在天山边缘及其邻近的稳定地块上，其中至少有一些发生在大陆岩石脆性行为不被高度预期的地方。所有这些地震的反向机制和它们与以前俯冲和后来碰撞和底侵稳定块体的接近以及它们与上覆天山的相互作用是解释这种极端的线索。
We have redetermined focal depths of moderate and major earthquakes with reported lower-crust and upper-mantle depths that have occurred in Tien-Shan, since the availability of broad-band array data. Records of earthquakes at global arrays have been used for identification and modelling of depth phases in order to make accurate estimation of focal depths. Our results show that half of the purportedly deep earthquakes are indeed originating from depths attributable to middle-crust and lower-crust regions. Also one exceptional event in the northern foreland of Tien-Shan in Junggar Basin is located in the upper mantle at the depth of 64 km. Such unusually deep earthquakes for intraplate continental tectonic domain are all located at the margin of Tien-Shan with its adjacent stable blocks and at least some of them have occurred where the brittle behaviour of continental rocks is not highly expected. The reverse mechanisms of all these earthquakes and their proximity to formerly subducting and later colliding and underplating stable blocks and their interactions with overlying Tien-Shan are clues to explain this extremity.