地震研究

利用祁连山地区(36°～42°N,96°～104°E)38个台站2014年8月—2015年12月的垂直分量连续背景噪声记录,获得了台站对之间的互相关函数和瑞利面波相速度频散曲线,采用基于射线追踪的面波频散直接反演方法,得到了观测台站下方5～40 km深度范围内的S波速度分布图像。结果表明:在5 km深度处,速度结构分布特征与地表构造分布存在一定的相关性,松散沉积层厚度影响明显; 在18 km深度处,S波速度横向不均匀性明显,呈现为高低速相间不同尺度大小的区域性。同时,5～20 km深度范围内速度随深度增加而逐渐增加,其变化幅度为0.2 km/s; 在30 km深度处,祁连和门源地区高低速相间分布明显; 在35～40 km深度,随深度增大,祁连山北缘断裂带、托莱山断裂、冷龙岭断裂带以北地区为高速区,以南为低速区。

Using the vertical component of continuous background noise records of 38 stations located in the Qilian Mountains(36°N ～ 42°N,96°E ～ 104°E),and the record time was from August 2014 to December 2015,then we obtained the cross correlation function of all seismic station pairs and the velocity dispersion curve of Rayleigh wave.The velocity distribution of the S wave in the depth range of 5 ～ 40 km and is obtained by using the direct inversion method of surface wave dispersion based on ray tracing.The result shows that there is a certain correlation between the velocity structure distribution and the tectonic distribution at the depth of 5 km.And the thickness of the sedimentary layer has obvious effect.The S-wave velocity has an obvious lateral heterogeneity and shows different scales of the regional at the depth of 18 km.Meanwhile,the velocity increases with the depth,and the variation range is 0.2 km/s at the depth of 5～20 km.And the high and low speed phases of Qilian and Menyuan areas are obviously distributed at a depth of 30km.The north of the Qilian Mountains,the Tuolaishan fault,the Lenglongling fault zone,the north of the Lenglongling fault zone,and the south of the Lenglongling fault zone,which may be a manifestation of different blocks at the deep boundary in the depth of 35～40 km.

引言
1 数据处理及结果分析
2 结论

图1 祁连山地区台站分布和构造背景图<br/>Fig.1 Distribution of seismic stations and tectonic setting in Qilian Mountains

图1 祁连山地区台站分布和构造背景图
Fig.1 Distribution of seismic stations and tectonic setting in Qilian Mountains

图2 所有台站构成的台站对互相关函数<br/>Fig.2 Cross-correlation functions of all the seismic station pairs

图2 所有台站构成的台站对互相关函数
Fig.2 Cross-correlation functions of all the seismic station pairs

图3 台站对AXX-JFS相速度频散曲线测量示意图<br/>Fig.3 Example of Rayleigh wave velocity dispersion curve of seismic station pairs AXX-JFS

图3 台站对AXX-JFS相速度频散曲线测量示意图
Fig.3 Example of Rayleigh wave velocity dispersion curve of seismic station pairs AXX-JFS

图4 不同周期反演使用的路径数<br/>Fig.4 Ray path numbers at different periods inversions

图4 不同周期反演使用的路径数
Fig.4 Ray path numbers at different periods inversions

图5 平均速度模型<br/>Fig.5 Average velocity models

图5 平均速度模型
Fig.5 Average velocity models

图6 不同周期面波射线路径分布<br/>Fig.6 The surface wave ray paths at different periods

图6 不同周期面波射线路径分布
Fig.6 The surface wave ray paths at different periods

图7 初始模型(a)、(b)及不同深度6 km(c)、18 km(d)、30 km(e)、40 km(f)的检测板测试<br/>Fig.7 Checkboard tests of input models(a)、(b),and different depth at 6 km(c)、18 km(d)、30 km(e)、40 km(f)

图7 初始模型(a)、(b)及不同深度6 km(c)、18 km(d)、30 km(e)、40 km(f)的检测板测试
Fig.7 Checkboard tests of input models(a)、(b),and different depth at 6 km(c)、18 km(d)、30 km(e)、40 km(f)

图8 面波走时残差标准差随迭代次数的变化示意图(a)及面波走时残差分布图(b)<br/>Fig.8 Variation of the standard deviation of surface-wave travel-time residuals with the iteration number(a)and distribution of surface wave travel-time residuals(b)

图8 面波走时残差标准差随迭代次数的变化示意图(a)及面波走时残差分布图(b)
Fig.8 Variation of the standard deviation of surface-wave travel-time residuals with the iteration number(a)and distribution of surface wave travel-time residuals(b)

图9 不同深度的剪切波速度分布图<br/>Fig.9 Shear wave velocity maps at different depths

图9 不同深度的剪切波速度分布图
Fig.9 Shear wave velocity maps at different depths

图10 剪切波速剖面<br/>Fig.10 Shear wave velocity profiles

图10 剪切波速剖面
Fig.10 Shear wave velocity profiles

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备注

引言

1 数据处理及结果分析

2 结论

期刊信息