Categorization of basaltic lava flows through avulsion angles, The
Botvin, Nina
Botvin, Nina
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2024-12
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Basaltic lava flows are characterized by low effusion rate, low viscosity, and >20 km length eruptions, with the main composition being iron and magnesium-rich and low in silica. The general morphological geometries of individual lava flows follow a fanlike structure, avulsing into complex channel networks, exhibiting similar traits to river systems (i.e., deltas, fluvial fans, and alluvial fans). Unlike deltas and fluvial fans, the processes that lead to the creation of fan-shaped deposits in lava flows are poorly documented and understood. Following pre-established methodologies created for these river networks, we characterized and quantified the angle at which the lava flows avulse. With ArcGIS Pro, we mapped lava flow structures and assessed each individual avulsion angle present (N=206). Preliminary results from Mauna Loa in Hawaii, Poco do Fogo in the Galapagos, and Cerro Azul in Cape Verde—all being basaltic shield volcanoes derived from hotspots—show an average avulsion angle of 53.1° ± 5.6°. These results indicate that there may be a standardized pattern in which these flows form, which could aid us in possible volcanic hazard mitigation and the identification of unknown flow patterns on extraterrestrial bodies, such as Mars. Additionally, when comparing the river structures to the basaltic lava flows, there is a noteworthy resemblance between the fluvial fan angle (at 55°, stated in published literature), and the average angle of the lava flow avulsions (at 53.1°). Since there is a similarity between the two avulsion angles, there appears to be a fundamental control on these avulsion processes, despite the notable differences in the fluid properties (i.e., water vs lava).
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Copyright of the original work is retained by the author.