In order to better understand the attenuation characteristics in the crust of the central and western Tien Shan orogenic belt, we investigate both Q p and Q s values by applying the extended coda-normalization method. We estimate the frequency-dependent attenuation of both P and S waves in the frequency band of 1.0–20.0 Hz using data from local networks. The average frequency relations of Q p and Q s have been derived as Q p = (61 ± 9) × f (1.21±0.08) and Q s = (77 ± 6) × f (1.11±0.04) by fitting a power-law frequency dependence model for the study region. The low Q 0 and high η values indicate that the central and western Tien Shan is a tectonically and seismically active region. We also find lateral variations of both Q p,s and Q s / Q p values, reflecting complex tectonic structures in the study area. In general, the relatively high-attenuation areas corresponding to tectonically active regions are found beneath mountainous ranges in the central Tien Shan whereas the relatively low-attenuation areas are associated with stable regions, such as Fergana Basin and Issyk-Kul Lake. Besides, regions in the central Tien Shan with Q s /Q p > 1 are likely partially saturated with fluids or rich in scattering heterogeneities, whereas regions in the western Tien Shan display Q s /Q p < 1, possibly suggesting almost complete fluid saturation.

中文翻译：

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中西天山地壳高频P波和S波衰减

为了更好地了解天山造山带中西部地壳的衰减特征，我们采用扩展尾归一化方法研究了Q p 和Q s 值。我们使用来自本地网络的数据估计了 1.0-20.0 Hz 频段内 P 波和 S 波的频率相关衰减。Q p 和 Q s 的平均频率关系已通过拟合幂导出为 Q p = (61 ± 9) × f (1.21±0.08) 和 Q s = (77 ± 6) × f (1.11±0.04) -研究区域的规律频率依赖模型。低 Q 0 和高 η 值表明中西部天山是构造和地震活动区。我们还发现 Q p,s 和 Q s / Q p 值的横向变化，反映了研究区复杂的构造结构。一般来说，在天山中部的山脉之下发现了与构造活动区相对应的相对高衰减区，而相对低衰减区与稳定区有关，如费尔干纳盆地和伊塞克湖。此外，天山中部Q s /Q p > 1的区域可能部分被流体饱和或具有丰富的散射非均质性，而天山西部区域显示Q s /Q p < 1，可能表明流体几乎完全饱和.