TUBES: a multidisciplinary project for understanding lava tube formation and preservation at Vesuvius and Etna.

Volcanic eruptions are potentially catastrophic phenomena that could have a huge impact on the environment and society. Effusive eruptions can generate large lava flow fields reaching great distances from the main vent, expanding along a volcano flank by developing channels and structures whose shape and extension depend on magma properties (e.g. viscosity, density and composition), topographic features of the ground (slope and roughness), effusion rate and emplacement duration. The formation of lava tubes is one of the main causes which determine the further maximum extension of a lava flow. The development of a stable crust around a moving lava, caused by cooling, significantly decreases the exchange of heat between lava and the atmosphere. This phenomenon is extremely significant in the case of volcanoes producing voluminous lava effusions and characterized by a steady effusion rate (e.g. Hawaii and Etna), but it was described also in explosive volcanoes with a low rate of lava flow production (e.g. Vesuvius). Previous studies focused on qualitatively describing the development of lava tubes in lava flow fields, but only few works examined quantitatively the physical process of lava tube formation. The project TUBES (undersTanding lava tUBe formation and preservation) is focused on a detailed volcanological, petrological, physical (e.g. rheological) analysis, structural analysis (e.g. guided wave analysis, acoustic emission testing) and numerical modeling of the effusive phase of Vesuvius and Etna, focusing on understanding the mechanisms behind the formation of lava tubes, expanding our knowledge about the processes at the basis of lava flow emplacement providing vital information for volcanic hazard and risk assessment on such highly urbanized volcanic areas. Moreover the results of our studies, and especially on the connection between surface lava flow morphology and lava tube size, might help discover more tubes both on Earth and other planets and improve cosmic exploration.