Approaches to estimation of seismic effect of mass explosions in quarries on underground mining excavations via opening-underground method of elaboration of apatite-nepheline deposits have been expounded. Experimental researches in full-scale conditions made the base for on the conclusions for determination of critical speed of rock shift and emperical dependence for defenition of the radius of seismic dangerous zones under effect of explosions have been shown for mine deposits at OJSC “Apatite” have been refenited. have been shown.