基于密集台阵研究2019辽宁抚顺M2.4矿震震源参数

分析矿震破裂机制及微震的时空分布能够为矿区灾害评估提供更多的有效信息.本研究基于密集台阵观测对2019年11月12日辽宁抚顺2.4级矿震开展震源参数研究,震源机制解显示地震破裂包含明显的非双力偶分量,表现为体积压缩的塌陷机制,且震源深度较浅,最佳拟合矩心深度为0.6 km.同时,对11月3日—25日记录的连续地震波形开展微震扫描,新检测出324个微震事件(-0.5~2.0级),定位结果显示在M 2.4矿震发生前M>1.0级事件显著增多,且在矿震位置存在近南北向的微震条带分布,微震序列随时间向深部迁移(约1.5 km),暗示存在断层活化迹象.结合震源破裂机制,我们认为此次事件与矿区塌陷破裂密切相关,同时伴随先存断裂的剪切滑动.本研究表明,基于密集台阵观测的地震矩张量反演和微震检测研究,对判定矿震类型及防范矿区灾害具有重要的研究意义.

Source characterization of the 2019 M2.4 earthquakes induced by Fushun,Liaoning mining based on a dense seismic array

Analyzing the focal mechanism of mining earthquakes and the spatio-temporal distribution of microseismic events can provide key information for hazard assessment in mining areas.In this study,we infer the source parameters of the 12 November 2019 Fushun,Liaoning,M 2.4 earthquake based on the data from a dense seismic array.The focal mechanism shows that the source process contains a significant non-double couple component with volume closure,and the best-fitting centroid depth is about 0.6 km.Meanwhile,we detect and locate the microseismic events from continuous waveforms,and obtain a new catalog of 324 events with magnitudes ranging from-0.5 to 2.0.The result shows that the number of M>1.0 events significantly increased before the M 2.4 mining earthquake.In addition,a north-south earthquake sequence migrating toward deeper depth occurs in the mining earthquake area,which implies the reactivation of the pre-existing fault.Our results suggest that the M 2.4 mining earthquake is associated with the mine cavity collapse and a sympathetic shear slip on the pre-existing fault.Our study also demonstrates that the seismic moment tensor inversion and microseismic event detection based on dense seismic stations are an effective approach to identify the source type of mine earthquakes and prevent disasters in the mining area.