| 穿过青藏高原的面波传播路径与速度结构 |
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| 引用本文： | 陈虹,黄忠贤.穿过青藏高原的面波传播路径与速度结构[J].地球物理学报,1998,41(Z1):270-280. |
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| 作者姓名： | 陈虹 黄忠贤 |
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| 作者单位： | 国家地震局地壳应力研究所, 北京 100085 |
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| 摘 要： | 利用时频偏振分析技术分析穿过青藏高原不同地区的基阶Love波的偏振方向，确定不同周期的Love波到达台站的入射方向对于大圆的偏离．结果表明，在青藏高原内部传播的Love波传播路径基本不偏离大圆路径，穿过青藏块体及川滇西部低速区边界的Love波明显偏离大回路径低速区（青藏高原及川滇西部）的边界区域速度变化梯度大，对路径影响大．低速区内部路径偏离不明显，内部速度变化梯度比边界区域速度变化梯度小．低速区内大约在青藏高原中部位置是面波速度最低的地方．面波路径对于大圆路径的明显偏离，是由于速度结构的横向不均匀性造成的．利用已知的相速度分布，采用射线追踪方法正演计算的结果与实测结果在偏离方向上是一致的，但偏离角的值则比实测值小．
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| 关 键 词： | 青藏高原 面波传播路径 时频偏振分析 横向不均匀性 面波射线追踪 |
| 收稿时间： | 1997-08-08 |
TRAVEL PATHS OF SURFACE WAVES ACROSS THE QINGHAI-XIZANG PLATEAU AND THE VELOCITY STRUCTURE |
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| CHEN HONG,HUANG ZHONG-XIAN.TRAVEL PATHS OF SURFACE WAVES ACROSS THE QINGHAI-XIZANG PLATEAU AND THE VELOCITY STRUCTURE[J].Chinese Journal of Geophysics,1998,41(Z1):270-280. |
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| Authors: | CHEN HONG HUANG ZHONG-XIAN |
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| Institution: | Institute of Crustal Dynamics, SSB, Beijing 100085, China |
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| Abstract: | A technique called time-frequency polarization analysis was applied to study thePOlarization direction of fundamental hove waves across different areas of Qinghai--Xizangplateau. The deviations of the incident direction which Love waves arrive'at the station indifferent peneds to the great circle paths were thus determined. The results show that Love waves propagating within the Qinghai--Xizap plateau didn't deviate to the great circle paths LOve waves across the border zone of low velocity of Qinghai--Xizang plateau and western Chuandian area deviate obviously to the great circle paths. The velocity gradient in border zone of Qinghai--Xizang plateau and western Chuandian is large and affect the paths badly. Paths travel within the low velocity zone did not deviate obviously, the velocity gradient in Qinghai--Xizang plateau is smaller than in herder zone of the plateau. The position Of lowest velocity zone is about at the middle of Qinghai--Xizang plateau. The observed deviations of the Love wave paths are caused by the lateral heterogeneities of the velocity structure. Phase velocity grid model （4°× 4°） of different peneds is comPOSed using the results of 3--D velocity structure inversion. The deviations of Love waves across the phasevelocity model were calculated using ray tracing method. The results revealed that the phase velocity model produces deviations smaller but of the same sign to the Observed deviations. |
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| Keywords: | Qinghai-Xizang plateau Travel paths of surface wave Time-frequence polarization analysis Interal heterogeneity Ray tracing of surface wave |
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