Results of Deep Soundings in Europe

Abstract

In the first half of the XX century, there appeared new approaches to deep induction soundings. The theory of magnetovariation as well as magnetotelluric soundings was formulated just before the World War Two. Spatial derivatives of response functions (induction arrows) were obtained for the long periods. New phenomena have been detected by this method: secular variations of the Earth’s apparent resistivity and the rapid changes of induction arrows over the last 50 years. The first ones can be correlated with the number of earthquakes and the second ones—with geomagnetic jerks in Central Europe. Extensive studies of geoelectrical structure of the crust and mantle were realized in the frame of a series of international projects. New information about geoelectrical structures of the crust in Northern Europe and Ukraine was obtained by deep electromagnetic soundings involving powerful, controlled sources. An influence of the crust magnetic permeability on the deep sounding results was confirmed.