An application of modern TEM technology for environmental investigations

Among numerous electromagnetic investigation techniques used for the earth research, the methods based on time domain processes seems to hold the lead. Compared to frequency domain methods time domain electromagnetic methods (TEM) have more high resolution with respect to electrical properties of the earth structure. Nowadays two types of TEM technique are most popular. One of them uses electric line for transmitting or receiving antenna (for example LOTEM), other uses closed loops both for transmitter and receiver. Because last modification operates only with magnetic field, it is less sensitive to local inhomogeneities of conductivity and more local. Sometimes, transmitter loop is used as recei ver one. Such modification is referred to as single loop modification. This modification provides a possibility to organize fast measurements. At the same time it is Iiable to distorting influence of superparamagnetic effect which can mask induction process. TEM-FAST instrument - Fig. 1 and technology which are the subject of our paper have been designed initially for Martian electromagnetic sounding. After some modifications they were applied for extended studies.