The MT technique is a development of the telluric method which exploits certain natural earth currents (telluric currents) that propagate as sheets over vast areas on the earth. Their cause is attributed to several factors like the rotation of the earth, ionospheric currents, tropical storms, etc. These currents are interrupted and modified by large-scale natural electrical discontinuities like major geological contacts, folds, faults, shear zones, etc (Gandhi & Sarkar, 2016).
MT has become one of the most important tools in deep Earth research. MT method can resolve geoelectric structure from depths of tens of meters to depths of tens of kilometers depending upon signal frequency and resistivity of material being studied. Hence, depth interpretation based on MT data is much more definitive than that based on gravity or magnetic data (Vozoff, 1972).
The low frequencies employed in MT enable larger depth penetration of several kilo[1]meters and also the resistivity of the ground obtained will be close to DC resistivity. With the fast development of technology of low noise sensors and signal processing acquisition of data up to 500 Hz is now possible. Hence its use in exploration of deep-seated mineral deposits becomes viable as well as attractive. MT has been found by many operators to be a cost-effective way to enhance an exploration program (Gandhi & Sarkar, 2016).
Reference
Gandhi, S. M., & Sarkar, B. C. (2016). Chapter 5—Geophysical Exploration. In S. M. Gandhi & B. C. Sarkar (Eds.), Essentials of Mineral Exploration and Evaluation (pp. 97–123). Elsevier. https://doi.org/10.1016/B978-0-12-805329-4.00012-0
Vozoff, K. (1972). The magnetotelluric method in the exploration of sedimentary basins. GEOPHYSICS, 37(1), 98–141. https://doi.org/10.1190/1.1440255
