Drone-borne aeromagnetic survey in in Kvikne, Innlandet

Abstract

As part of an NGU-funded project led by I. Henderson, a drone-based aeromagnetic survey was conducted in two areas near Kvikne (Innlandet, central Norway) to create high resolution magnetic maps of abandoned copper mines. This project is part of the ongoing collaboration between NGU and the Norwegian government aimed at exploring secondary resources. This report details the acquisition, processing, and visualization of the datasets collected during the survey, presenting the results as detailed maps. The two geophysical surveys covered a total area of 15 km², with 138 and 91 flight lines, respectively. Despite challenging weather conditions—especially strong winds in the second survey area—limited accessibility, and poor network access, the surveys were successfully completed in August 2024. The NGU utilized a DJI M300 multipurpose drone equipped with a Sensys MagDrone R3, a three component fluxgate magnetometer securely mounted on the drone’s landing gear. With a sampling rate of 200 Hz and a sensitivity of 150 pT, the magnetometer is well-suited for detecting weak magnetic anomalies, making it ideal for this high-resolution geophysical survey. Weighing just 1 kg, the system is lightweight and integrates seamlessly with the drone. The surveys were conducted at a flight speed of 5 m/s with a route spacing of 30 meters. The spacing between parallel flight lines was adjusted based on the altitude during data acquisition. UGcS software was employed for topographic draping, allowing the drone to maintain a consistent altitude of 50 meters above ground level. This altitude was chosen to ensure clearance from the tallest trees and to accommodate the steep terrain. A total of 77 flights were required to cover the two areas. The raw magnetic data were processed using proprietary software, which compensates for the drone’s magnetic interference, generating a clean magnetic dataset. Custom codes were applied for data processing, and the results were gridded and visualized using GMT software. Topographic data with a 10-meter resolution were sourced from the Hoydedata.no website.