## 2 Engineering Background  
### Overview of the Working Face  
This study selects the 3308 working face of the Yangcheng Coal Mine for analysis. Located in Jining, southwestern Shandong Province, the 3308 fully mechanized caving face lies in the deep area of the third mining district of the Yangcheng Coal Mine. The working face spans 150 m in width and advances over a 650 m length, with an average coal seam thickness of 7.5 m. To the east, it borders the 3306 working face, with the DF60 fault to the north, the \(-920\) shaft bottom station to the south, the goal of the 3306 working face to the west, and the DF56 normal fault to the east. The layout of the working face is shown in Figure 1. To ensure safety and stability during mining, a 3 m wide pillar is left between two adjacent longwall panels. This pillar width provides adequate support for the area between the mining panels, preventing large-scale surface subsidence or localized rock damage during mining.  
In the shallow adjacent area of the 3308 working face, there is an extensive goat formed by the 3306, 3304, and 3302 working faces. Due to the steep dip angle of the #3 coal seam, the overlying strata of the shallow goat in adjacent working faces have not fully collapsed. The subsidence and collapse of overlying strata in the inclined direction of the goat may negatively affect the coal seam and roof of the 3308 working face, which is one of the primary factors influencing mining-induced earthquakes in the 3308 working face.  
Based on the mining experience of the Yangcheng Coal Mine, the 3306 working face, which has similar geological and production conditions to the 3308 working face, had already been mined before this study. The zone of destruction of the roof rocks above the post-mining space for the 3306 working face (mainly due to periodic pressure causing roof rock damage) was approximately 15 to 20 m. During the microseismic research of the 3308 working face, which was in its initial extraction stage, the zone of destruction of the roof rocks above the post-mining space was estimated to be around 25 to 30 m based on the microseismic location, source mechanism, and microseismic response before and after the high-energy mining-induced earthquake event on 20 December. After the targeted seismic measures recommended in this study were implemented at the Yangcheng Coal Mine, no further high-energy mining-induced earthquakes or rockbursts occurred, and the zone of destruction of the roof rocks above the post-mining space decreased to the 15 to 20 m range, similar to that of the 3306 working face under similar working conditions.  
The primary seam mined in the 3308 face is the No. 3 coal seam, which exhibits a tendency for rockburst. The seam has a dip angle ranging from 26\({}^{\circ}\) to 30\({}^{\circ}\), with an average dip of 28\({}^{\circ}\). It is black with a vitreous luster and a brownish-black streak. Compositionally, it is mainly bright coal, with lesser amounts of vitrinite, minor dark coal, and trace fiber coal. It has a stepped fracture and a banded structure, with the middle to upper portions mostly consisting of blocky, hard coal. The structure of the coal body in this face generally appears banded; however, near the faults, structural stress effects cause the coal to exhibit fractured, granular, and pulverized structures. The average coal seam thickness is 7.5 m, classifying it as a stable thick seam. The occurrence characteristics of the coal seam at the working face are shown in Figure 2.  
Figure 1: Structural layout of the 3308 working face in relation to surrounding mining areas and faults.  
Figure 2: Occurrence characteristics of the coal seam at the working face.