三峡库区秭归段浅层速度结构和孕震环境  

Shallow velocity structure and seismogenic environment in the Zigui section of the Three Gorges Reservoir region of China

作　　者：胡锦涛 谢军 危自根 金超 Hu Jintao;Xie Jun;Wei Zigen;Jin Chao(School of Earth Sciences and Engineering,Hebei University of Engineering,Hebei Handan 056038,China;Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430077,China;State Key Laboratory of Geodesy and Earth’s Dynamics,Wuhan 430077,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Beijing 100037,China)

机构地区：[1]河北工程大学地球科学与工程学院,中国邯郸056038 [2]中国科学院精密测量科学与技术创新研究院,中国武汉430077 [3]大地测量与地球动力学国家重点实验室,中国武汉430077 [4]中国地质科学院地质研究所,中国北京100037 [5]自然资源部深地动力学重点实验室,中国北京100037

出　　处：《地震学报》2023年第2期223-233,共11页Acta Seismologica Sinica

基　　金：自然资源部深地动力学重点实验室开发研究课题(J1901-16);国家自然科学基金(U20A2095);国家重大研究计划专项基金(92162105)联合资助。

摘　　要：收集了湖北省秭归地区24个流动地震台站2020年6—7月期间的垂直分量连续波形记录,利用背景噪声互相关得到了各台站之间的经验格林函数,提取了0.6—5 s周期范围内的瑞雷波群速度频散曲线,并反演获得了该区域近地表6 km以内的三维S波速度模型。结果显示:秭归盆地及其南部邻区的S波速度明显低于东侧断裂区的S波速度,与研究区不同构造地块的构造演化和沉积特征一致;2014年M_S4.2地震发生在研究区垂向高低速交界区;长江区域附近断裂区的S波速度明显降低,表明长江水渗透到断层区,因此秭归地区地震频发与三峡库水荷载和水渗透作用有关。After the impoundment of the Three Gorges Reservoir in 2003,shallow earthquakes occurred frequently,which had a great impact on local productions and lives.The study of shal-low velocity structure is of great significance for shallow seismic disaster assessment and disaster prevention and reduction in Zigui area. In this paper,based on the vertical component continuous waveform records of 24 mobile seismic stations in Zigui area of Hubei Province from June to July of 2020, the empirical Green’s functions between the stations are obtained by cross-correlation of the ambient seismic noise,the Rayleigh wave group velocity dispersion curves on the period 0.6−5 s are extracted,and the inversion for the three-dimensional S-wave velocity model is obtained within 6 km near the surface of the region. The results show that the S-wave velocity of Zigui basin and its south adjacent area is significantly lower than that of the eastern fault area,which is consistent with the structural evolution and sedimentary characteris-tics of different structural blocks in the studied area;an earthquake with MS4.2 occurred on the vertical high-velocity and low-velocity junction area of the study area in 2014. The S-wave velocity decreases obviously near the Yangtze River region in the fault zone,indicating that the Yangtze River water penetrates into the fault area. Therefore,the frequent occurrence of earthquakes in Zigui area is related to the water load and water infiltration of the Three Gorges reservoir.

关 键 词：秭归地区 地震背景噪声 瑞雷波群速度 浅层速度结构 

分 类 号：P315.2[天文地球—地震学]