## 3 Results and Discussion
Applications of the forecasting method resulted in formulating recommendations as to further mining operations in panel XVII/1, following the second rockburst event. In Section 2.2 relating to the seismic activity, the hypothesis was formulated stating that a considerable reduction of seismic risk (and the risk of the next rockburst occurrence) during continuing mining operations was unlikely as long as the same mining methods were employed. In consideration of workers' safety, certain modifications were necessary in order to reduce mining-induced seismicity, particularly in the high-energy range. Assuming that the registered seismic activity could be attributable to activation of burst-prone main roof formations caused by deformations to their original structure, it is reasonable, therefore, to seek solutions aimed to limit the extent of roof deformation in the course of future mining works. It was established that the major determinants of future roof deformation in the analysed panel include the following:  
* Vertical roof displacement (deflection) over the development openings and old excavations;
* Areas opened by panelling works in the orebody. In regard to the first aspect (i.e., roof deflection), it is suggested that the roof control method be changed and the hydraulic filling be employed regardless of the actual height of the face entry drivage and system requirements. The other aspect (presence of openings) is associated with intensity of mining operations, being the function of the rate of face advance and its length. As reducing the rate of face advance (to date it is \(\sim\)15 m/month) might enhance the risk of roof caving, it was suggested that the face range be shorter. Along the cluster of galleries T,W-243 the panel is divided into two sections (blocks A and B) in which the operations should progress sequentially, starting from section A abutting on the old excavation on the left-hand side (Figure 3). The elements that should positively reduce the exposed roof area are the width of the opening size, expressed as the distance between the working faces in the panelling and in liquidation works. Additional simulations were performed to highlight the distribution of the shear strain elastic energy density in the burst-prone strata in the function of the variable development opening size (Figure 10). The results were obtained for the cross-profile A-B located in the axis of the A block and are related to the mining conditions when the mining operations are re-commenced (in accordance with recommendations quoted in the previous section) and the rate of face advance should be 50 m. The reference plot (black coloured, Figure 10) depicts the conditions prior to the rockburst event (in Year 6), when the average width of the opening size was \(\sim\)270 m; the remaining plots reveal the gradual decrease in this parameter, down to 200, 150 and 100 m.  
It is readily apparent that variability of the energy density factor expressed as its maximum values over the undisturbed rock body related to variable width of the opening size is relatively small. However, on account of major fluctuations observed in the development zone, it is suggested that appropriate distance should be maintained between the panelling lines and liquidation works, not exceeding the minimum value (150-170 m) necessary for the mining processes. These recommendations were implemented and, from the time perspective, were found to be merited producing the desired results. From the year when mining operations were resumed (Year 7) until the end of panelling works in block A within the panel XVII/1 (Year 10), the registered mining-induced seismicity (Table 3) was significantly lower than in the last 6 years (Table 2). During the 4-year period, 205 tremors were registered with energy \(\geq 10^{3}\) J (including 13.1% of events in the energy class \(\geq 10^{5}\) J), with the energy released totalling 7.49 \(\times\) 10\({}^{7}\) J (including 97.3% of events in the energy class \(\geq 10^{5}\) J).