【摘要】 近年来，四川盆地南缘(川南)中强地震频次增多和地震活动性增强，2021年9月16日四川省泸州市泸县M_S6.0地震的发生再次引起国内外学者对川南地区深部孕震环境和潜在地震危险性的密切关注.为了探究泸县6.0级地震震区的深部结构特征，本文基于最新布设于震区70个短周期密集地震台站的观测资料，采用背景噪声成像法构建了泸县M_S6.0震区三维S波精细速度结构.研究结果表明，研究区内喻家寺向斜和华蓥山断裂带东/西支深部速度结构表现明显非均匀性，喻家寺向斜构造区在深度3.0 km内表现为低速，随着深度增加，速度逐渐增大.华蓥山断裂带东、西支除了存在局部低速非均匀体，整体上表现为NE-SW展布的高速特征.泸县震源区西侧4.0～6.0 km深度呈现低速异常，东侧则表现高速异常分布，主震位于高低速分界带，震区周边存在大范围的明显线状几何特征的地震分布，震源深度优势分布层位主要集中在3.0～5.0 km之间.综合已有的资料分析，主震西侧的低速异常区指示着该处可能存在流体，推测泸县6.0级地震可能是在区域构造应力和流体扰动的作用下，泸县震区的先存隐伏断层发生错动所致.更多还原

【Abstract】 In recent years, the frequency of moderate and strong earthquakes and the intensity of seismicity in the southern margin of Sichuan Basin increase significantly. The occurrence of the Luxian M_S6.0 earthquake on 16 September 2021, located in Luzhou City of Sichuan Province, have once again attracted the attention of domestic and foreign researchers for the seismogenic environment and potential seismic hazards in southern Sichuan. In order to explore the deep structure around the source area of the Luxian M_S6.0 earthquake, based on the dense array composed of 70 short-period seismic stations, a high-resolution 3-D S wave velocity model is constructed with the method of ambient noise tomography. The results show that the velocity varies significantly beneath Yujiasi syncline and Huayingshan fault′s eastern/western branches. The velocity structure beneath the Yujiasi syncline exhibits low within the depth of 3.0 km, and as the depth increases, the velocity gradually increases. The eastern and western branches of the Huayingshan fault zone shows high velocity in the NE-SW direction generally, except for several local low velocity anomaly zones. It shows low velocity anomaly to the west of the Luxian earthquake source area at depths of 4.0～6.0 km, and high velocity to the east. The Luxian earthquake epicenter is located at the boundary of the high and low velocity zone. The focal depth of the aftershock sequences are mainly between 3.0 and 5.0 km. Combined with the previous studies, the low-velocity zone located west of the epicenter may be interpreted as the effect of fluids. It is speculated that the occurrence of the Luxian M_S6.0 earthquake may due to the dislocation of the pre-existing hidden fault under the action of regional tectonic stress and fluids disturbance.更多还原