R. Berkman, V. Korepanov (Lviv Centre of Institute of Space Research, Naukova str., 5-A, 290601, Lviv, Ukraine)

Last time the idea of the existence of electromagnetic (EM) precursors of such seismic hazards as earthquakes and volcano eruptions is widely supported. Both electric and magnetic components of the EM radiation are experimentally studied and each component reflexes its own side of the corresponding physical phenomena. Because of very low level of these signals the problem of obtaining as low as possible sensitivity level is one of the most important. It is difficult to give some advantageous recommendations as to the noise reduction of electrical measurements . But for magnetic ones last improvements in search-coil magnetometers (SCM) design and manufacturing give hope both to decrease considerably the noise level of the sensors and to rise their interferencies rejection ratio. A set of wide-band and narrow-band SCM covering the frequency range from 0.0001 Hz to 500 kHz is described together with some new possibilities of noise reduction and interferencies suppression. The possibility to get the noise level less than 1 femtoTesla and to suppress more than 120 dB the interferencies is discussed. Experimental sensitivity curves of the developed SCM are presented.