The study of the deep structure of the Earth's crust is of great interest forboth applied (e.g. mineral exploration) and scientific research. For this theelectromagnetic (EM) studies which enable one to construct the distributionof electrical conductivity in the Earth's crust are of great use. The mostcommon method of EM exploration is magnetotelluric sounding (MT). Thispassive method of research uses a wide range of natural geomagneticvariations as a powerful source of electromagnetic induction in the Earth,producing telluric current variations there. It includes the measurements ofvariations of natural electric and magnetic fields in orthogonal directionsat the surface of the Earth. By this, the measurements of electric fields aremuch more complicated metrological processes, and, namely, they limit theprecision of MT prospecting. This is especially complicated at deep soundingwhen measurements of long periods are of interest. The increase in theaccuracy of the electric field measurement can significantly improve thequality of MT data. Because of this, the development of a new version of aninstrument for the measurements of electric fields at MT – both electricfield sensors and the electrometer – with higher levels relative to theknown instrument parameter level – was initiated. The paper deals with thepeculiarities of this development and the results of experimental tests ofthe new sensors and electrometers included as a unit in the long-periodmagnetotelluric station LEMI-420 are given.
展开▼
