基于震相自动检测方法的秭归地区三维速度成像  

Three-Dimensional Velocity Imaging at Zigui Area Based on Automatic Seismic Phase Detection Method

作　　者：史哲 廖武林 姚运生 童广勤 SHI Zhe;LIAO Wulin;YAO Yunsheng;TONG Guangqin(Key Laboratory of Earthquake Geodesy,CEA,40 Hongshance Road,Wuhan 430071,China;Hubei Key Laboratory of Earthquake Early Warning,40 Hongshance Road,Wuhan 430071,China;Institute of Disaster Prevention,465 Xueyuan Street,Sanhe 065201,China;Basin Hub Operation and Management Centre of China Three Gorges Corporation,Environmental Protection Building,Three Gorges Dam Area,Yichang 443133,China;Hubei Provincial Key Laboratory of Operation and Safety of High Dams and Large Reservoirs,Environmental Protection Building,Three Gorges Dam Area,Yichang 443133,China)

机构地区：[1]中国地震局地震大地测量重点实验室,武汉市430071 [2]地震预警湖北省重点实验室,武汉市430071 [3]防灾科技学院,河北省065201 [4]中国长江三峡集团有限公司流域枢纽运行管理中心,湖北省宜昌市443133 [5]高坝大库运行安全湖北省重点实验室,湖北省宜昌市443133

出　　处：《大地测量与地球动力学》2024年第12期1280-1286,1311,共8页Journal of Geodesy and Geodynamics

基　　金：国家自然科学基金(42174177);中国长江三峡集团有限公司科研项目(0799275)。

摘　　要：收集三峡地区2019~2022年30个台站记录的连续波形数据,使用PALM程序完成研究区的微震检测和地震定位,然后采用双差层析成像方法反演得到秭归地区水平分辨率为0.05°、垂直分辨率为3 km的三维速度结构图像。主要结论如下:1)三峡重点监视区地震事件分布范围与前期相比基本保持不变,但随着水库蓄水时间的增加,库区地震事件震源深度相较10 a前有所加深,巴东地区平均深度增加2.3 km,秭归地区平均增加2.6 km;2)秭归地区速度结构图像显示,近地表地壳速度横向变化差异比较大,速度分布主要受地质构造影响,仙女山断裂带、长江及其支流附近区域因库水渗透程度不同,P、S波及波速比呈现不同的变化特征,库水渗透深度可能已超过8 km;3)仙女山断裂带附近地震事件呈近陡直排列,其震源深度从近地表至12 km均有分布,与倾向SW、倾角70°~80°的仙女山断裂带关系密切,该断裂北端至长江的相对高速区说明该区域节理裂隙发育不充分,岩石较完整,断裂可能未穿过该区域。We collect continuous waveform data recorded by 30 stations in the Three Gorges area from 2019 to 2022.We use the PALM program to complete the detection of microseismic events and earthquake location in the study area.Then,we employ the double-difference tomography method to invert and obtain a three-dimensional velocity structure image of Zigui area with a horizontal resolution of 0.05°and a vertical resolution of 3 km.The main conclusions are as follows:1)The distribution range of seismic events in the key monitoring area of the Three Gorges has remained basically unchanged compared to the previous period.However,as the reservoir water storage time increases,the depth of the earthquake sources in the reservoir area has deepened compared to 10 years ago,with an average increase of 2.3 km inBadong area and 2.6 km in Zigui area.2)The velocity structure image of Zigui area shows that there is a large difference in the lateral variation of crustal velocity near the surface,and the velocity distribution is mainly influenced by geological structures.The P-wave,S-wave,and velocity ratio show different characteristics of change in the areas near the Xiannüshan fault zone and the Yangtze river and its tributaries with different degrees of reservoir water penetration,and the depth of reservoir water penetration may have exceeded 8 km.3)The seismic events near the Xiannüshan fault zone are nearly vertically arranged,and their source depths are distributed from near the surface to 12 km,closely related to the Xiannüshan fault zone with a trend of SW and a dip angle of 70°-80°.The relatively high-velocity area from the north end of the fault to the Yangtze river indicates that the joint fracture development in this area is insufficient,the rocks are relatively intact,and the fault may not have penetrated this area.

关 键 词：三峡水库地震 PALM地震自动检测与精定位 模板匹配 双差层析成像 

分 类 号：P315[天文地球—地震学]