Seismogenic ULF magnetic activity — Peculiarities of registration

A big number of publications confirm that ultra low frequency (ULF) magnetic precursors were recorded from few weeks up to few hours before earthquakes (EQs). For the detection of magnetic precursors at the background of more powerful sources it is necessary to have magnetic field sensors with wide dynamics and minimum possible spectral noise density. The requirements to a dedicated magnetometer and its main parameters are discussed and the example of such an instrument realization is given. The newly developed technology of EQ-related ULF signals selection is presented. The attempts of this technology application in order to select the candidates for EQ precursors are discussed, basing on the natural ULF signals, collected in India by multi-point synchronized magnetometer network.