Recent advances in magnetotelluric instrumentation and field results

摘要

The electromagnetic methods of Earth exploration have considerable development last years in Ukraine.The magnetotelluric sounding (MTS) remains one of the most efficient geophysical methods for the study of the Earth's interior with depths from first tens of meters till several hundreds of kilometers. There are some important requirements to the corresponding instrumentation which has to cover the frequency range from DC to ~ 10 kHz with as high as possible sensitivity. This problem is discussed in details in the presentation. The magnetic sensors selection criteria are given which allow using appropriately the induction coil or flux-gate magnetometers. The peculiarities of super-wide band induction coil magnetometers design are presented. Finally two major challenges in the instrumentation development to get reliable data in the so called "dead band" (from ~1 to 0.1 Hz) and to prolong the apparent resistivity plots till the periods ~100 000 second and more are discussed. The ways to complete both these problems and to develop a high-class magnetotelluric instrument as well as the results of its use are outlined in the presentation.