## 4 Analysis of the Microseismic Event Monitoring Results  
### Analysis of the Detection Results of the Number of Microseismic Anomalies over Faults  
Figure 6 shows the characteristics of the changes in the number of microseismic events at the five faults over the Pulang copper mine. The microseismic events occurred more frequently from April to August 2018 and from April to July 2019, with the relatively highest number of microseismic events at the five faults on the FIII-2 fault and the lowest number on the FIII-1, among which an abnormal number of microseismic events occurred on 14 June 2019 near the intersection area of the western bottom pushing line and the FI-1, FII-1, and FII-2 faults (as marked by the green dashed line in the figure). To address this abnormal number, the fault model was introduced with the monitoring range as the boundary as shown in Figure 7. In the figure, the yellow is the F1 fault, the red is the F2 fault, the blue is the F3 fault, the purple is the F4 fault, and the green is the F5 fault. Figure 6: Characteristics of the changes in the number of the microseismic events at the faults. From Figure 7, it can be seen that microseismic events existed near each fault, among which more microseismic events were generated near the F1, F2, and F4 faults, and the microseismic events were mainly concentrated near the agglomerate groove and pull-bottom advance line, indicating that the rupture events of the rock body caused by the agglomerate groove, pull-bottom, and excavation blasting, the stress redistribution after exiting the mine, and the fault activation showed a certain clustering phenomenon, and gradually developed in all directions along the fault. The microseismic events in the western and northern parts of the first mining area were more concentrated, indicating that the rock rupture in the western and northern parts of the first mining area was more serious, which was consistent with the larger subsidence of the surface 2# chute and its northwestern part. Through the analysis of the fault model, the precursor warning information of the large rupture and destabilization of the rock near the fault was obtained; the pulling-bottom speed and ore output should be controlled in the subsequent production, and the influence of the fault activation on the stability of the rock should be fully considered to strengthen the support measures. In total, 228 microseismic events were monitored within the green circle during the time period of a number of anomalies at the fault, as shown in Figure 8, in which 213 microseismic events were monitored in the event concentration from 14:00 to 15:00 for about one hour, with the magnitude range \(-\)3.6\(\sim\)\(-\)2.3. For this microseismic event aggregation phenomenon, a module was established in the region, and its apparent volume and energy analysis were calculated. Figure 8: Distribution of the microseismic events at fault. The red lines indicate the distribution of faults. The green circles in the left panel represent the large number of microseismic events collected in a short period of time. For this phenomenon, a module was created in the right figure and its apparent volume and energy analysis were calculated. Figure 7: Distribution of the microseismic events at the faults. (**a**) Horizontal distribution. (**b**) Vertical distribution. The different colored spheres represent the degree of aggregation of microseismic events near different faults, and the direction of the arrow indicates the development of stress distribution and fault activation due to copper mining. The anomalous time interval of the region was intercepted and plotted with the time distribution characteristics of the cumulative apparent volume and energy index as shown in Figure 9. The cumulative apparent volume increased rapidly from 14:00 to 15:00 on that day, while the energy index did not fluctuate, indicating that the rock body in the region produced a microrrupture in a short period of time, and no precursor of the rock explosion and large-scale rock collapse was found.