Drone-based Magnetic Surveys for Lava Tube Detection in Volcanic Terrains: Preliminary Results from Etna and Vesuvius

Magnetic surveying is a key geophysical technique for detecting subsurface structures due to its sensitivity to lithological and structural variations. Recent advances in lightweight, high-sensitivity magnetometers have enabled their integration with UAV platforms, allowing rapid, high-resolution data acquisition in complex terrains. This approach improves logistical flexibility, reduces survey times, and ensures safe, non-invasive investigations in areas otherwise difficult to access.

Within the PRORIS initiative (https://www.proris.it/), our team conducted UAV-based magnetic surveys to identify and characterize lava tubes in volcanic environments, focusing on Mount Etna and Mount Vesuvius. These campaigns aimed primarily at testing and validating innovative geophysical methodologies through collaboration among research institutions.

The surveys employed different magnetometric systems, including MagArrow and Magnimbus (in gradiometric configuration), mounted on UAVs. Multiple acquisition strategies were explored, such as varying flight altitudes and sensor-to-platform distances, to assess their impact on signal quality and anomaly resolution. UAV deployment proved essential for achieving dense coverage and safe operations in steep, inaccessible areas.

Preliminary results revealed distinct magnetic anomalies consistent with subsurface lava tubes, some confirmed by historical speleological data. However, interpretation was complicated by partially collapsed tubes and sediment infill, which often share magnetic properties with surrounding rock, reducing anomaly contrast. These challenges highlight the importance of optimizing sensor configurations and survey design.

The primary goal of these initial campaigns was methodological: evaluating the effectiveness of different magnetometric setups and acquisition approaches for lava tube detection. Future work will focus on 3D modeling of detected structures using magnetic inversion techniques and integrating magnetometry with complementary geophysical methods, particularly ground-penetrating radar (GPR). This multi-sensor approach is expected to enhance resolution and reliability of subsurface models, supporting applications in volcanic studies and analog environments.

By combining UAV-borne magnetometry with advanced processing strategies and other geophysical tools, this research contributes to the development of robust remote sensing techniques for subsurface exploration. These efforts expand the capabilities of geophysical investigations in challenging terrestrial settings and provide a foundation for future applications in planetary analog studies.