Seismic Clustering Analysis for Detecting Seismic Hazards Induced by Geological Anomalies and Residual Coal Pillars: A Case Study of Mining in a Protected Coal Seam

Seismic hazards in underground coal mines are frequently triggered by geological anomalies and residual coal pillars, posing severe threats to safe mining. A protected seam longwall in a Chinese coal mine was used as a case to analyse the seismic clustering characteristics under the combined influence of the B4 anticline and a 30-m-wide overlying residual chain pillar. A simulation-testing-based source locating accuracy (STSLA) method was used to study the vector characteristics of seismic location errors in the longwall. A new seismic clustering index, the Number of Possible Clustered Events (NPCE), was proposed to quantify fracture connectivity in the coal-rock mass while reducing the influence of locating errors. The spatial–temporal evolution of NPCE, seismic event frequency, and energy magnitude was compared. Results show that NPCE exhibits a strong positive correlation with imminent high-energy seismic events and outperforms conventional indicators in recall rate and overall early-warning performance. The confusion matrix method demonstrates that NPCE achieves a better balance between precision and recall, especially at high pre-warning thresholds. NPCE = 0.7 is determined as the optimal threshold for seismic hazard risk identification. The proposed method provides a reliable approach for seismic-data-based seismic hazard early warning.