Abstract:
Due to the complex record form and difficulty in type recognition of seismic events in the Changzhi area of Shanxi Province, this paper takes the
ML 2.8 earthquake that occurred at the junction of Xiangyuan and Lucheng in Changzhi, Shanxi on December 15, 2019 as an example to analyze the source characteristics of the Xiangyuan-Lucheng earthquake from the aspects of structural environment, spectrum characteristics, source parameters, rupture mechanism, simultaneous seismic activity and on-site investigation. The results show that the Xiangyuan-Lucheng earthquake has the characteristics of relatively low frequency distribution, low stress drop, and large rupture scale compared with earthquakes in the same region, and the source depth is at the depth of the high-low velocity conversion layer. It has a generally consistent main stress axis direction with four
ML≥3.0 seismic activities that occurred intensively in the same region later, and it is also close to the direction of the high principal stress in the NNE direction shown by the existing media in the source area. Therefore, this study believes that the Xiangyuan-Lucheng earthquake was an earthquake induced by the regional stress enhancement superimposed on the local existing NNE high principal stress, which was induced in the mining area. This may be related to the fracturing of water injection in the mining area, which lubricates the fault section in the source area and reduces the friction coefficient, and the small stress change in the region activates the pre-existing fault.