## 2 Analysis of Rockburst Manifestation Characteristics
### Microseismic Characteristics Analysis  
Microseismic events are typically characterized by low energy release (in the order of joules to kiljoules), high frequency, and strong sensitivity to stress changes in surrounding rock masses. Their occurrence often precedes larger-scale dynamic failures such as rockbursts, thus serving as important precursors for early warning. In deep mining environments, especially under thick and hard roofs, the spatial clustering and temporal evolution of microseismic activity can reflect localized stress concentration, crack initiation, and gradual energy accumulation in the rock mass. To investigate the distribution characteristics and spatiotemporal evolution of rockbursts in the 21,103 working face, continuous monitoring and data analysis were conducted using a microseismic monitoring system during the face's operation. The spatial distribution of microseismic event frequencies and energies along the dip and strike directions were plotted, as shown in Figures 3 and 4, separately. Figure 1: Schematic diagram of the spatial relationship between the working faces in the No. 2-1 CS of Hulusu Coal Mine. Figure 2: Borehole stratigraphic profile of the No. 2-1 coal seam in Hulusu Coal Mine. Figure 4: The frequency and energy distributions of microseismic events along the strike direction of the 21,103 working face. Figure 3: The frequency and energy distributions of microseismic events along the dip direction of the 21,103 operating face. In Figure 3, microseismic events along the dip direction are primarily concentrated between the 21,103 return airway and the adjacent 21,102 goaf. Particularly within the range of approximately 60 m west of the return airway (close to the 21,102 goaf) to 100 m eastward inside the 21,103 working face, the frequency and energy of microseismic events significantly rise, with average values much higher than those in other areas. Over 70% of all monitored events are located in this zone. A noticeable rise in microseismic frequency and energy near the 21,102 goaf indicates the strong influence of the unstable roof structure in the old goaf and the associated stress transfer effects. The \"21,103 return airway\" region is a high-incidence area of microseismic activity and thus represents a critical zone for rockburst prevention and control. The frequent microseismic activity in this area reflects localized stress concentration and structural instability in the surrounding rock, necessitating enhanced support and monitoring to mitigate potential rockburst hazards. In Figure 4, most microseismic events and their associated energy are concentrated within a zone extending from 50 m behind the working face to 300 m ahead. Approximately 80% of microseismic events and over 90% of the total microseismic energy are located within this region, indicating that the active zone of roof movement is mainly situated in front of the operating face. This front region is the principal zone for stress release and rock failure, and thus constitutes the primary region for rockburst hazard control. In contrast, regions located more than 50 m behind the working face are less affected by mining-induced disturbance and have developed relatively stable goaf structures. Microseismic activity in these zones is significantly reduced, with only sporadic events observed. Some high-energy microseismic events may occur during the compaction of the goaf or due to the sudden failure of overhanging roof structures near the coal pillars, likely caused by stress redistribution in the surrounding rock. Additionally, approximately 10% of the microseismic events within the 50 m behind the face are associated with immediate roof collapse, rock fragmentation, and basic roof fracturing. In comparison, within the 300 m in front of the operating face, the strata are more prone to crack propagation, rupture, and intense energy release under mining-induced disturbance, making this area the primary danger zone for rockburst disasters.