Effect of variation of external and internal sources of magnetic field on the results of induction sounding
The induction soundings are based on variations of the external magnetic fields due to inducting currents in the conductive Earth. However changing of the source positions relatively the Earth can essentially change the sounding results. Besides this, the induction soundings fix the long period internal sources which are weakly connected with the skin depth of soundings. It turned out, that this effect in the Earth resistivity can be big enough especially for seismically active regions in Europe. These effects are considered in the present work.