The Sanjiang Lateral Collision Zone (SLCZ) in the SE margin of the Tibetan Plateau is a special area where several strike-slip faults intersect, resulting in strong deformation and frequent earthquakes. We employ seismic waveforms recorded by a dense temporary broadband array (SJ array) and regional permanent stations to construct more complete microseismic catalogs by the microseismic identification in the SLCZ. New microseismic catalogs effectively increase the number of small earthquakes, revealing the details of the fault structures and providing many more records for S-wave splitting (SWS) analysis. It provides with an uncommon opportunity to detect the detailed upper crustal anisotropy in the fault intersection zone of SLCZ and to dissect the influence of faults, such as the Lijiang-Xiaojinhe fault and Red river fault, on crustal deformation. The spatial distribution of SWS parameters suggests multiple disturbance mechanisms to the upper crustal anisotropy in the study zone. Spatial distribution of dual dominant polarization directions of fast S waves near the block boundary faults uncovers the stress-focus range. Strong deformation from SWS data indicates frequent local seismicity. It reveals the spatial upper crustal deformation indicated by SWS parameters is closely related to not only stress, fault and local structure, but also local seismicity.

中文翻译：

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空间变化的地壳变形表明青藏高原东南缘断层交叉处的地震活动：微震识别 S 波分裂的证据


位于青藏高原东南缘的三江横向碰撞带 （SLCZ） 是一个特殊区域，几个走滑断层相交，导致强烈变形和频繁地震。我们利用密集的临时宽带阵列 （SJ 阵列） 和区域永久台站记录的地震波形，通过 SLCZ 中的微震识别构建更完整的微震目录。新的微震目录有效地增加了小地震的数量，揭示了断层结构的细节，并为 S 波分裂 （SWS） 分析提供了更多记录。本研究为探测SLCZ断裂交汇带中详细的上地壳各向异性，并剖析漓江小金河断裂和红河断裂等断裂对地壳变形的影响提供了难得的机会。SWS 参数的空间分布表明研究区上地壳各向异性的多种扰动机制。块状边界断层附近快速 S 波的双主极化方向的空间分布揭示了应力-聚焦范围。SWS 数据的强烈变形表明局部地震频繁。它揭示了 SWS 参数指示的上地壳空间变形不仅与应力、断层和局部结构密切相关，而且与局部地震活动密切相关。