Validation of a New UAV Magnetic Prospecting Tool for Volcano Monitoring and Geohazard Assessment

Abstract

The use of unmanned aircraft vehicles (UAVs) in volcanological contexts is a key challenge in studying volcanoes and improving efficiency in the monitoring of volcanic activity. The coupling of ground and satellite measurements has been reinforced at an intermediate scale thanks to UAV measurements. Along with carrying out visible and infrared measurements, UAVs can conduct geophysical measurements for more in-depth studies. Magnetic field measurements are a powerful tool in volcanic contexts for (i) mapping structural contacts between formations of different ages or type, and (ii) imaging deep thermal anomalies and intrusive systems. Here, we focus on magnetic sensors, which are becoming operational, and in particular on a scalar system recently implemented on a light drone that can be deployed quickly and efficiently in the field. This paper presents several flight test results in order to discuss any artifacts of the UAV or environmental conditions in the magnetic measurements. The results of the comparison between simultaneous UAV and ground surveys are presented. We demonstrate that low altitude measurements are particularly relevant to well-imaged magnetic anomalies and their variation through time in a volcanic context. Some potential uses for this technology and associated applications are also discussed in the fields of exploring and monitoring active volcanoes, for the 4D imaging of volcanoes.

Application of a Drone Magnetometer System to Military Mine Detection in the Demilitarized Zone

“…However, installing multiple magnetometers is difficult and requires a larger drone. Larger drones create more magnetic noise and, therefore, suitable drone size is an important consideration [ 37 ].…”

“…Previous research has suggested that landmines may be detected by attaching one magnetometer to a small UAV (sUAV) [ 37 , 38 ]. The conditions for detecting landmines involve measuring magnetic anomalies and adjusting for the distance between the landmine and the sUAV [ 39 ].…”

“…To increase the probability of landmine detection, it is essential to maintain a constant altitude, a short distance (1–2 m) from the surface [ 39 ]. Research is underway to achieve this goal, but no reliable method has yet been described [ 37 ]. Processing of data obtained using UAVs follows existing procedures used for manned and airborne magnetism observations [ 40 ].…”

Indoor Mapping of Magnetic Fields Using UAV Equipped with Fluxgate Magnetometer

“…If we focus on the UAV applications dealing with magnetic field measurement or mapping, the research is mainly focused on the cost-effective airborne magnetic surveys for industrial and geoscientific applications [ 7 ] in exteriors. These applications not only involve geological and geophysical mapping [ 8 ], which can be performed thanks to the UAVs on a regional scale [ 9 ], but can also be used to perform magnetic surveys for geothermal exploration [ 10 ], volcano monitoring [ 11 ], and related geohazard assessments [ 12 ] for the evaluation of factors affecting gully headcut locations [ 13 ]. The magnetic sensors placed on the UAV boards can be used for mineral exploration and mining operations [ 14 ] or for the detection and identification of the orphaned oil and gas wells [ 15 ].…”

A Novel Noise Reduction Method of UAV Magnetic Survey Data Based on CEEMDAN, Permutation Entropy, Correlation Coefficient and Wavelet Threshold Denoising

“…UAV magnetic surveys can cover a wider range with a higher efficiency compared with the traditional terrestrial magnetic surveys, and are also easy to operate, have a low-cost, and have a good safety profile compared with manned aircraft magnetic surveys [3]. In addition, UAV-based magnetic surveys can also be carried out in areas that are difficult to access or that would pose a potential hazard to operators (e.g., near active volcanoes), which means that some gaps in traditional magnetic surveys can now be studied [4,5].…”