Aerial magnetic survey

AERIAL MAGNETIC SURVEY (EN: aeromagnetic survey; DE: magnetische Luftaufnahme; FR: lever aeromagnetique, photographie aeromagnetique; ES: levantamiento aeromagnetico; RU: аэромагнитная съемка) is the method for the measurement of the intensity of the geomagnetic field from the aeroplane or helicopter; it is conducted for the tectonic zonation, geological mapping, searches for the deposits of the useful minerals.

The aerial magnetic survey has been proposed and conducted by the Soviet scientist A.A.Logachev during the 1936 with the purpose of the searches for the deposits of the magnetic iron ores. For the aerial magnetic survey, there are mainly used the protonic and quantum aerial magnetometers (see the "Magnetometer" article).

The aerial magnetic survey is conducted according to the network of the parallel routes at the constant height above the level of the sea or the surface of the Earth. In the first case the altitude of the flight is monitored by the barometric altimeter, in the second case the altitude is monitored by the radio altimeter. At the mountains, the flights are performed also with the "matching" of the general forms and along the horizontals of the relief of the terrain. The planned position of the routes is determined with the help of the aerial photographic positioning and radio navigation systems. During the conducting of the aerial magnetic survey, they take into account the deviation (the influence of the magnetic field of the aeroplane) with the method of the placing of the magnetically sensitive element (EN: MSE; RU: МЧЭ) within the non-magnetic gondola, which is towed behind the aeroplane on the cable-rope, or with the help of the canceller of the interferences in cases of the rigid attachment of the MSE to the aeroplane. The variations of the geomagnetic field are registered at the special stations, which are being situated at the survey place, and also with the help of the base aerial magnetic networks, which are being created for the mutual linking of the measurements, and for the bringing them to the unified level (usually to the average annual values of the field at the nearest magnetic observatory).

The prospects for the usage of the aerial magnetic survey are associated with the increasing of the accuracy of the aerial magnetometers, which are designed for the measurement of the components of the intensity of the geomagnetic field, and also with the creation of the aerial magnetometers - gradiometers.