Propagation of Elastic Vibrations and Generation of Microseismic Emission in Loaded Rocks Samples under Dynamic Impact

The propagation of elastic vibrations in rock samples in compression and under impacts to failure is investigated experimentally. Under impacts, a signal of acceleration was recorded in the samples, and the spectral density was calculated to determine velocities of elastic vibrations. It is found that under increasing load up to a pre-failure value, the P- and S-wave velocities grow, and the S-wave velocity increases by more than 50%. The acoustic Q-factor rises by 70%. The energy of the microseismic emission under pre-failure loads is two times higher than under low loads, and the high-amplitude spectral components generated under pre-failure loading are reflective of large discontinuities being formed.