祁连山地区地震台阵浅层速度计算结果初探  

Preliminary Study on Shallow Velocity Calculation Results of Seismic Array in Qilian Mountains Region

作　　者：郭瑛霞 张丽峰[1] 黄浩[1] 胡维云 Guo Yingxia;Zhang Lifeng;Huang Hao;Hu Weiyun(Qinghai Earthquake Agency,Xining 810001,China)

机构地区：[1]青海省地震局,西宁810001

出　　处：《青海科技》2022年第5期161-165,175,共6页Qinghai Science and Technology

基　　金：青海省地震局项目“青海格尔木青藏高原内部地球动力学野外科学观测研究站专项”;“2022年青海省地震局地震科学基金课题”(2022B01);“2022年度震情跟踪定向工作任务”(2022010504)。

摘　　要：文章筛选了40个原始记录较好的祁连山北缘断裂带流动台阵垂直分量背景噪声资料,借助噪声面波成像反演方法,得到祁连山北缘断裂带及附近0.4~4.0 km深度范围内的S波速度空间分布特征。研究发现,在地壳浅部,各个深度的S波速度呈现出不同的区域分布,与浅部沉积层和地表构造特征分布存在密切关系。0.4 km深度、0.7 km深度的速度切片,主要受沉积层厚度影响呈现出显著的区域性分布。1.4 km深度、2.1 km深度的速度切片,在西秦岭北缘断裂附近、榆木山断裂以南、拖莱山断裂以北等断裂附近的围空地区为高速区。2.8 km深度、3.5 km深度的速度切片,只有中间台站对射线覆盖好的区域具有显著的高低速区,其他区域均有模糊性,明显区域与上述速度切片高低速区对应。总体范围内速度随深度的增加而逐渐增加,这种正梯度增加符合大陆地壳的速度变化规律。In this paper,the vertical component background noise data of the mobile bench array in the fault zone of the northern margin of the Qilian Mountains with good original records were screened,and the spatial distribution characteristics of the S wave velocity in the fault zone of the northern margin of the Qilian Mountains and its nearby depth range of 0.4~4.0 km were obtained with the help of the noisy surface wave imaging inversion method.It is found that in the shallow crust,the S-wave velocity at different depths presents different regional distribution,which is closely related to the distribution of shallow sedimentary layer and surface structure characteristics.The velocity slices at depths of 0.4 km and 0.7 km show significant regional distribution mainly affected by the thickness of the sedimentary layer.In the velocity section with a depth of 1.4 km and 2.1 km,the high speed zone is found in the surrounding open area near the faults in the northern margin of the West Qinling,south of the Yumushan fault and north of the Tuolai Mountain fault.In the velocity section at a depth of 2.8 km and 3.5 km,only the stations in the middle area coverd by the ray have a significant high and low speed zone,while the other areas have fuzziness.The obvious area corresponds to the high and low speed zone in the above velocity section.The overall velocity increases gradually with the increase of depth,and this positive gradient increase is consistent with the velocity variation law of continental crust.

关 键 词：祁连山地区 背景噪声 互相关函数 面波成像 

分 类 号：P315[天文地球—地震学]