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天然地震的 P、S 波在青藏高原地区的传播特征表明:(1)在高原地区不存在明显的“影区”现象;(2)振幅随距离的变化,在10°～12°出现极小值,在20°附近出现极大值;(3)2°到30°的走时曲线可以用4段直线来描述,推断的上地幔结构为:界面深度(公里) P 波速度(公里/秒) S 波速度(公里/秒) Vp/Vs53±2 8.15±0.03 4.58±0.03 1.78196±36 8.37±0.08 4.59±0.11 1.82463±83 9.68±O.19 5.37±0.34 1.80736±121 11.21±0.26 6.19±0.20 1.81(4)高原地区上地幔顶层的温度可达800℃～1000℃,岩石层的厚度约为200公里。文中还简要地讨论了本文结果的构造意义。
The characteristics of P and S waves of natural earthquakes in the Qinghai-Tibet Plateau indicate that: (1) there is no obvious phenomenon of “shadow” in the plateau; (2) the amplitude of the earthquakes is extremely small at 10 ° ~ 12 ° (3) The travel time curve from 2 ° to 30 ° can be described by 4 straight lines. The inferred upper mantle structure is: Depth of interface (km) P wave velocity (km / s) S wave velocity (km / sec) Vp / Vs 53 ± 2 8.15 ± 0.03 4.58 ± 0.03 1.78196 ± 36 8.37 ± 0.08 4.59 ± 0.11 1.82463 ± 83 9.68 ± O.19 5.37 ± 0.34 1.80736 ± 121 11.21 ± 0.26 6.19 ± 0.20 1.81 ( 4) In the plateau, the temperature of the top layer of the upper mantle reaches 800 ℃ ~ 1000 ℃, and the thickness of the rock layer is about 200 km. The paper also briefly discusses the structural significance of the results of this paper.