<p>Strong mining-induced seismicity (SMIS) severely hinders the safe and efficient operation of coal mines and poses a significant threat to public safety. Investigating the causes of SMIS is essential for the targeted prevention and control of such events. In this study, the 1208 working face of the Shilawusu coal mine in the Ordos mining area was studied as the engineering background. Principal component analysis (PCA), combined with hybrid moment tensor (MT) inversion method, was applied to improve the accuracy of the MT results, and the failure mechanism of SMIS was further analyzed. The stress inversion method, originally assuming shear failure as the sole failure mechanism, was refined. The refined method significantly reduces errors in the principal stress direction and stress ratio, which arise from fault/slip deviation when performing stress inversion for non-shear failure seismic sources. This method is more suitable for stress field inversion in coal mining environments, thus revealing the controlling effect of maximum principal stress (<i>σ</i>₁) compression on SMIS. Stereographically projecting the fracture planes, seven dominant fracture planes in the strata were fitted. By calculating their instability tendencies, the risk of seismicity induced by fracture plane activation due to stress field variations was assessed. Integrating observations of surface subsidence and internal rock layer damage, the entire process of seismicity induced by tensile and shear failure of the ultra-thick Cretaceous strata was described.</p>