Field studies of seismic blast waves have been carried out at a number of iron ore enterprises of the country. At the KMA open pits it was confirmed that the seismic effect of mass explosions depends on the epicentral distance between the block and the object and on the mass of the charge in the group. The dependences of vibration velocity for quarries and mines differ by the seismicity coefficient, which is almost three times less for underground mass explosions than for mass explosions at quarries.
