Morphometric analysis of lava tubes

Lava tubes are interesting features for their fundamental role in understanding the formation of lava flow fields on Earth and their implication on the emplacement of lava terrains across the solar system and could provide insights into the thermal evolution of rocky planetary bodies. Moreover, being natural shields, they could have a key role in protecting astronauts against micrometeorite impact, space weathering and extreme thermal excursion. For all these reasons, in the last decades, lava tubes have experienced a growing interest as planetary analogues from the scientific community and space agencies. These features have been detected on the surface of Mars and the Moon as sinuous collapse chains, through satellite imagery interpreted as surface evidence of collapsed sections of subsurface conduits (Sauro et al., 2020). Since we have not yet had access to the subsurface of Mars and Moon a direct approach to the analogues will help us to understand what is hidden in the underground of these planetary bodies.Active lava tubes work as thermally efficient conduits, where the minimisation of heat loss allows the transport of lava flows over long distances (Tomasi et al., 2022), for their origin, three main genetic processes were proposed: overcrusting, shallow inflation and deep inflation (Sauro et al., 2020). It has been recently proposed that the latter forms by magma exploitation of buried weak horizons such as a pyroclastic layer (Sauro et al., 2020; Tomasi et al., 2022). The main two lava tube patterns are single tubes which can be sinuous or rectilinear and braided tubes with splitting branches and reconnections (Sauro et al., 2020). In addition, lava tubes show a huge variety of morphologies and differences in size and shape, potentially associated with their genetic process and specific eruptive (effusion rates, trend and duration of the eruption) and slope parameters.Thanks to 2D surveys in the regional inventories, it has been shown in karst caves that it is possible to perform morphometric analyses, extracting several dimensional parameters and indices (Piccini, 2011). We have applied a similar approach to lava tubes, resulting in a dataset with 27-dimensional parameters and morphometric indices. These analyses have shown how morphometric indices, through a statistical approach, are useful for classifying lava tubes. In particular, the Aspect Ratio, Vertical Range, Area of the Plan Map and Plan Length have highlighted the relationship between morphologies and genetic processes and the possible evolution of these volcanic caves. Acknowledgments:This study was carried out within the Space It Up project funded by the Italian Space Agency, ASI, and the Ministry of University and Research, MUR, under contract n. 2024-5-E.0 - CUP n. I53D24000060005.References:PICCINI, Leonardo. Recent developments on morphometric analysis of karst caves. Acta Carsologica, 2011, 40.1.SAURO, Francesco, et al. Lava tubes on Earth, Moon and Mars: A review on their size and morphology revealed by comparative planetology. Earth-Science Reviews, 2020, 209: 103288.TOMASI, Ilaria, et al. Inception and Evolution of La Corona Lava Tube System (Lanzarote, Canary Islands, Spain). Journal of Geophysical Research: Solid Earth, 2022, 127.6: e2022JB024056.