High resolution shallow crustal shear wave velocity structure of Anyuan mining area and its adjacent region in Jiangxi Province, China

Abstract High-resolution seismic image is critically important for mining minerals. In this work, we collected seismic data from a local dense seismic array of 154 stations around the Anyuan mining area and its adjacent region of Pingxiang City, Jiangxi Province in South China, and applied the ambient noise tomography (ANT) method to image the shear wave velocity structure in the mining area. Shallow crustal velocities at depths less than 3.3 km were determined by direct inversion of Rayleigh wave group velocity dispersion curves at the period range of 0.5–5.0 s. Overall, the S-wave velocity structure has a tight correlation with surface geological and tectonic features in the study area. Influenced by the depression of sedimentary structure and the coal mining activities in the Pingxiang-Leping region, the shear wave velocity structure in the shallow crust of the Anyuan Mine and its adjacent areas presents obvious low-velocity anomalies. The shear wave velocity structures around the Anyuan fault (AYF) and Wangkeng fault (WKF) zones exhibit low-velocity anomalies from the ground surface to ~ 3.3km underground, and the low-velocity anomalies at depths less than 1.2 km could be related to the sedimentary environment of coal mine and the coal mining activities, while the low-velocity anomalies at depths below 1.2 km are caused by the presence of fracture medium, oil and gas in the fault zone. The shear wave velocity changes sharply across the AYF and the characteristics of the velocity change interface show the AYF is inclined toward the northwest and the depth of its extension reach to ~ 3km underground. Based on the depth of the obvious low-velocity intrusive anomalies beneath the Anyuan mining area, we deduce the mining depth of the Anyuan coal mine area exceeded 1 km underground.