惠少兴, 吴建平, 颜文华, 范莉苹. 2019: 陕西及邻区瑞雷波相速度层析成像. 地震学报, 41(2): 181-193. DOI: 10.11939/jass.20180081
引用本文: 惠少兴, 吴建平, 颜文华, 范莉苹. 2019: 陕西及邻区瑞雷波相速度层析成像. 地震学报, 41(2): 181-193. DOI: 10.11939/jass.20180081
Hui Shaoxing, Wu Jianping, Yan Wenhua, Fan Liping. 2019: Rayleigh wave phase velocity tomography in Shaanxi and its adjacent regions. Acta Seismologica Sinica, 41(2): 181-193. DOI: 10.11939/jass.20180081
Citation: Hui Shaoxing, Wu Jianping, Yan Wenhua, Fan Liping. 2019: Rayleigh wave phase velocity tomography in Shaanxi and its adjacent regions. Acta Seismologica Sinica, 41(2): 181-193. DOI: 10.11939/jass.20180081

陕西及邻区瑞雷波相速度层析成像

Rayleigh wave phase velocity tomography in Shaanxi and its adjacent regions

  • 摘要: 本文利用布设于陕西及其邻区的喜马拉雅二期流动地震台阵和区内的固定地震台网共计257个台站于2014—2015年记录到的连续波形资料,采用基于图像分析的相速度提取方法,得到了7 185条瑞雷波相速度频散曲线,反演获得了周期为5—40 s的瑞雷波相速度分布图像,其最小分辨率约为20 km。结果表明:各周期瑞雷波相速度图像具有明显的横向不均匀性,能够较好地反映出地壳及上地幔顶部的地质构造特征。周期为5—10 s的瑞雷波相速度分布与地表地质构造密切相关,且高低速异常的分界线与地块边界高度吻合;周期为15 s的瑞雷波相速度分布图像显示出,大部分断陷沉积盆地(渭河、天水等盆地)表现为低速异常,表明此区域的沉积层厚度较大;周期为20—40 s的相速度分布则受地壳厚度影响较大,青藏高原东北缘始终呈现出明显的低速异常,鄂尔多斯地块中、下地壳以高速异常为主,但周期为20—30 s的相速度低速异常区分布于青藏高原沿六盘山逆冲褶皱带并一直延伸至鄂尔多斯内部,由此推测该区域地下介质中存在一定程度的物质交换和融合。

     

    Abstract: In this paper, we used the vertical component of continuous wave data in Shaanxi and its adjacent regions recorded by total 257 stations in the broadband stations of the portable seismic array deployed under the project " China Seismic Array: Northern Part of North-South Seismic Belt” and fixed seismic network from 2014 to 2015. The 7 185 phase velocity dispersion curves of Rayleigh waves are obtained by using the phase velocity extraction method based on image analysis, then the phase velocity dispersion are used to reconstruct the phase velocity maps at period of 5-40 s with the minimum resolution about 20 km. The results show that the phase velocity maps better reflect the geological structure characteristics of the crust to uppermost mantle due to the obvious lateral heterogeneity of the phase velocity distribution. The phase velocity distribution of Rayleigh wave in the short period (5−10 s) is closely related to the surface geological structure, the boundary between high-velocity anomaly and low-velocity anomaly is consistent well with the boundary of the block. In the 15 s period, on the phase velocity maps most of the rifted sedimentary basins (the Weihe, Tianshui, etc.) still exhibit low-velocity anomalies, indicating that the basin may have thicker sedimentary layer. The phase velocity distribution in 20−40 s period is greatly affected by the thickness of the earth’s crust, the northeastern Tibetan Plateau has always been characterized by obvious low-velocity anomalies, and the Ordos block exhibits a high-velocity anomalies in the middle to lower crust. However, the low-velocity anomaly of the 20−30 s period extends from the Tibetan Plateau along the Liupanshan thrust fold belt to the interior of Ordos, therefore it is speculated that there is a certain degree of material exchange and fusion in this area.

     

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