Testing of the New HSG Soundings in Central Europe

Analysis of the historical data measured by the geomagnetic observatories has been carried out using the modern approach suggested recently for the horizontal spatial gradient (HSG) soundings. This method based on the modified differential relation between the magnetic field spectra and impedance. The method requires several independent sources of the exciting field to detect the new impedance and its derivatives inside observatory groups. They have been estimated from the hourly observatory data by two different data processing routines: in the time and frequency domains for the period range from about 3 hours up to two days. Two groups of the observatories situated in Central Europe above the East European and Phanerozoic western plates have been chosen for analysis of impedance. The obtained responses are in a rather good correlation with the geomagnetic depth sounding (GDS) ones estimated earlier at those observatories for longer periods. The induction arrows have been estimated from the impedance derivatives (the gradient tippers) for the groups of observatories that is why they cannot be compared with the previous results for the separate observatories.