Coupling Seismic, Gravity and Magnetic Surveys for the Investigation of Planetary Lava Tubes: A Terrestrial Analog Case Study in Lanzarote (Spain)

Lava tubes are subsurface volcanic conduits formed during effusive basaltic eruptions and are considered key targets for planetary exploration. Orbital remote sensing on the Moon and Mars has identified numerous collapse pits interpreted as possible surface expressions of underlying lava tube systems. However, the limited resolution of current orbital data sets severely restricts our ability to determine their three-dimensional geometry, internal structure, continuity, and in some cases even their existence. With upcoming planetary missions planning to deploy ground-based geophysical instruments, robust and transferable strategies for subsurface lava tube detection and characterization are urgently needed. Terrestrial lava tubes represent valuable analogs for developing and testing such approaches. Previous investigations have often relied on single geophysical methods, resulting in ambiguous interpretations. Here we present a multi-method geophysical study of the “Cueva de Los Naturalistas,” a well-preserved lava tube located in the UNESCO Global Geopark of Lanzarote (Canary Islands), an excellent analog for extraterrestrial volcanic environments. We conducted high-resolution, profile-based, active and passive seismic surveys integrated with gravity and magnetic measurements. Seismic anomalies above the cavity correlate with negative gravity and magnetic signatures, while upward continuation of magnetic data reveals the tube's subsurface continuity. Joint 2.5D Hamiltonian Monte Carlo inversion of magnetic and gravity data, combined with 3D structural modeling, constrains the tube's geometry and structure, demonstrating the effectiveness of an integrated geophysical approach for lava tube exploration and characterization. The proposed geophysical workflow could be easily adapted to future robotic and human exploration of other celestial bodies.