甘东南地区基于射线追踪面波频散三维成像
Direct Inversion of Surface Wave Dispersion for Three-dimensional Shallow Crustal Structure Based on Ray Tracing in Southeastern Area of Gansu Province

利用甘肃东南部地区（32.2°~33.5°N，102.7°~105.5°E）62个流动台站的垂直分量连续背景噪声记录数据，经过处理得到了所有可能台站对的面波互相关函数和瑞利波相速度频散曲线，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5~20 km深度范围内的剪切波速度分布图像。结果表明，5 km深度对应的剪切波速度横向变化与地表断裂带分布和沉积层厚度存在一定的相关性，西秦岭北缘断裂带以北地区多为低速区，漳县盆地、临洮盆地低速是沉积层较厚 （近几km） 的一种表征；10 km深度对应的剪切波速度在西秦岭北缘断裂以南、临潭-宕昌断裂、礼县-罗家堡断裂之间的区域为低速区，光盖山-迭山北麓断裂周围为高速区；在15 km深度左右，迭部-白龙江断裂附近形成了高低速相间的分块结构；在18 km深度左右，西秦岭北缘断裂带附近呈现高速特征，10~18 km深度范围内速度随深度逐渐增加，其变化幅度一般为0.2 km/s。
We used the vertical component of data from 62 flow stations recording continuous background noise to determine the possible interaction of surface-wave-related functions and Rayleigh-wave-phase velocity dispersion curves in southeastern Gansu (32.2°~33.5°N, 102.7°~105.5°E). We used the ray-tracing surface-wave-dispersion direct inversion method for five observation stations within a 20-km shear wave velocity distribution image depth range. The results show that there is a correlation between shear wave velocity corresponding to a 5-km depth and lateral variations in the thickness distribution of the deposited layer in the surface fault zone. In addition, the northern West Qinling fault zone is mostly a low-speed zone. Also, the Zhangxian and Lintao Basins belong to one type of characterization of the deposited thick layer (the last a few kilometres). About a 10-km depth corresponds to the shear wave velocity in the south margin fault of Lingbei Xiqin. The Lintan-Dangchang fault in the Lixian-Luojiabao area is between the low-fracture velocity zone, with light covered mountains-stacked high speed around the Northern Piedmont fault zone. There is a block structure of high and low rendering features near the Diebu-Bailong River Ling fault at about a 15-km depth. At about a 10~18-km depth range, the speed gradually increases with depth and the magnitude of the change is about 0.2 km/s.