Separation of crystalline rocks by elastic properties is crucial in determining the applicability of seismic exploration for solving geologic problems in ancient shields. In Northern Karelia, special parametric seismic soundings were carried out in 1958 by the Spetsgeofizika office and the All-Union Research Geological Institute with the participation of the Leningrad Mining Institute. During these observations, made in conjunction with depth seismic sounding (DSS), the same receiving equipment was used: low-frequency seismic receivers of the SP-15 type and seismic stations SS-26-51D, reconstructed for low-frequency reception. Most of the records of elastic waves from explosions are made at the same bandwidth as the GSZ (5- 15 Hz), a smaller part - at medium-frequency filtering (30-50 Hz).