Recalibrated Relationship of P-Wave Velocity in a Coal Seam with Depth in the South-Western Upper Silesian Coal Basin

P-wave velocity in coal seams increases with depth and reflects the in situ stress state in the rock mass. Anomalous velocity can indicate changes in the stress state resulting from various mining and geological disturbances. This information could contribute to the more efficient mining of coal at greater depths, particularly in seismically prone areas. The empirical relationship between P-wave velocity in coal seams and depth, developed by Dubiński in 1989, enables the determination of the magnitude of the velocity anomaly. However, this relationship was determined based on measurements taken to a depth of approximately 900 m. Currently, mining in the south-western Upper Silesian Coal Basin extends to greater depths, reaching around 1300 m. This study aims to update the empirical relationship for calculating reference P-wave velocities in coal seams by including new data. The archival 252 measurements were combined with 74 new velocity data from greater depths up to 1281 m. Regression analysis revealed that the updated power model offers a more reliable description of velocity changes in coal seams with increasing depth. This updated model can be used to identify anomalous stress zones and implement special protective measures in endangered mine workings. Our findings may contribute to reducing the risk of dynamic phenomena and enable more efficient exploitation of deep-seated coal seams.