Seismic, magnetic and gravity investigations of Lunar lava tubes: An Earth-analogue case study from Lanzarote island (Spain)

Lava tubes are subsurface volcanic conduits formed during effusive basaltic eruptions and are increasingly recognized as key targets for planetary exploration. On the Moon, orbital remote sensing imagery has revealed numerous collapse pits suggesting the presence of subsurface lava tube systems. These structures are of high scientific and exploration interest, as they may provide stable thermal environments, effective radiation shielding, and protection from impact hazards. However, the geophysical characterization of lunar lava tubes remains challenging, as current low-resolution orbital remote sensing techniques offer limited insight into their three-dimensional geometry, internal structure, spatial continuity and, in most cases, even their existence.

As future missions plan to deploy surface-based geophysical instruments, there is a growing need for robust and transferable integrated strategies to characterize subsurface lava tubes. Terrestrial lava tubes provide essential analogues for developing and validating such approaches, yet most existing studies rely on single geophysical techniques, limiting the completeness of subsurface interpretations.

Here, we present a comprehensive multi-method geophysical investigation of the lava tube “Cueva de Los Naturalistas” in the UNESCO Geopark of Lanzarote (Canary Islands), a well-established analogue for lunar volcanic terrains due to its basaltic composition, recent volcanic history and well-preserved lava tube system. We have conducted high-resolution, profile-based, active and passive seismic surveys coupled with magnetic and gravity investigations to image and characterize the subsurface geometry of the lava tube. Both passive and active seismic analyses reveal anomalous behaviour above the cavity, which strongly correlates with a negative magnetic and gravity anomaly. Joint 2D magnetic & gravity inverse modelling and 3D structural modal analysis of the roof of the lava tube allow us to constrain the tube’s location, dimensions and internal structure, highlighting the complementarity and suitability of the methods used and reducing ambiguities inherent in single-technique approaches.

Our results demonstrate the effectiveness of integrated seismic, magnetic and gravity surveying for lava tube characterization and provide a methodological strategy that can be adapted to future robotic and human missions on our natural satellite. This study contributes to closing a critical gap in our ability to assess subsurface cavities on the Moon and other planetary bodies.