GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 Vertical gradient measurements using MFAM in a UAV-borne magnetic survey F. Accomando 1 , A. Fedele 2 , G. De Natale 2 , R. Somma 2 , C. Troise 2 , G. Florio 1 1 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse – Università di Napoli “Federico II”, Italia. 2 Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano The magnetic method is one of the oldest geophysical exploration techniques. It represents a fast, cheap, reliable, and non-invasive method playing an important role in geological, archaeological, and engineering applications, from small to large scales of investigation. In the last decade, the introduction of new miniaturized and lightweight magnetometers coupled with modern unmanned aerial vehicles (UAV) allowed the development of drone-borne magnetometry. These advances opened new data acquisition possibilities reducing costs, time and risk and performing surveys with a very high resolution and uniform areal coverage. In many instances the use of drone magnetometry is advantageous, as in the case of the survey of large areas, or in the case of an area covered with dense vegetation or characterized by a rough terrain with hazardous ground condition. 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. Our UAV magnetic system is based on the Geometrics Micro-Fabricated Atomic Magnetometer (MFAM) in the “Development kit” version, housed in a specially developed custom bird. To allow the total field vertical gradient measurements, the bird was modified adding a fin-shaped additional polystyrene frame to house and separate the two MFAM sensors and preserve the aerodynamics of the system. We show that the vertical gradient data need a special processing to obtain reliable results. In fact, the noise generated by the drone platform must be treated differently for the two sensors. Our drone-borne vertical gradient data results compare well with ground data, acquired in the same area as a benchmark. Our experiment paves the way for interesting new fields of application of drone-borne magnetic surveys.