Magnetotelluric survey equipment typically consists of a data logger, solar panel and 12V battery, three magnetic sensors and two electric sensors. Each electric sensor is comprised of a pair of electrodes which are separated by 50-100 m and buried in moistened ground (Figure 3). The electrode is housed in a (jam tin-sized) cylinder (13 cm-long, 7.5 cm diameter). The electric sensors are set up with both a north-south and east-west orientation.
The magnetic sensors are induction coils. Three induction coils are used, and they are oriented to measure the vertical and horizontal magnetic field components. The sensors are contained within 2 metre -long PVC pipes. During the monitoring time, the horizontal sensors are buried approximately 20 cm deep and the vertical sensor is installed up to 1 m deep in the ground and stabilised using an above-ground frame. Wires connecting the sensors to the data logger will also be deployed, and these may need to be protected from damage.
Modern technology allows to obtain reliable and affordable 3D resistivity models, describing at best the resistivity structure of any field. Three-dimensional modelling is usually preceded by preliminary 1D and 2D modelling. Magnetotellurics is the main geophysical technique employed in many exploration projects, since it can provide a reliable multi-dimensional resistivity imaging of the subsurface in very rugged areas and at affordable costs.