Moment Tensor Analysis for the Local Magnitude 3.7 Seismic Event on June 25, 2022, Near Hinton, Central Alberta

Source mechanisms help understand the faulting behaviour and the evolving stress field in the subsurface. This study investigates the source mechanism of an event with a local magnitude (ML) of 3.7 that occurred near a blasting site, 19 km east of Hinton, central Alberta, on June 25, 2022. The amplitude-based method was used to invert the seismic moment tensor of the event. The amplitudes of compressional P-waves and shear S-waves recorded at multiple seismic stations of regional networks were used in the inversion. The synthetic amplitudes of the ground displacements were computed using ray tracing and a one-dimensional velocity model. Then the solution was found through a least-squares inversion scheme. The inverted moment tensors of the ML = 3.7, June 25, 2022, event were compared with the inverted moment tensors of six suspected blasts and an earthquake (ML = 1.68) near Hinton. The analysis revealed that the ML = 3.7, June 25, 2022, event was a blast, rather than a natural earthquake unrelated to the blasting or an event induced by the blast as initially suspected.