Vertical gradient measurements using MFAM in a UAV-borne magnetic survey

The magnetic method is one of the oldest geophysical exploration techniques playing an important role in different fields of application. The introduction of new miniaturized and lightweight magnetometers integrated with modern unmanned aerial vehicles (UAV) allowed the development of drone-borne magnetometry opening new data acquisition possibilities which allow reducing costs, time, and risk and performing surveys with a very high resolution and uniform areal coverage. In this study, we present one of the first attempts of drone-borne vertical gradient measurements, with examples of application in archaeological sites. In fact, the vertical gradient is usually measured for enhancing the resolution in ground magnetic surveys, but only in very few cases, its measure was attempted in drone-borne surveys. To allow the total field vertical gradient measurements, the bird containing the MFAM magnetometer in the “Development kit” version was modified adding a fin-shaped additional polystyrene frame that allows to separate the two MFAM sensors. The results show that the noise generated by the drone platform must be treated differently for the two sensors. Our tests open the way for interesting new fields of application of drone-borne magnetic surveys.