Volcanic conduit migration over an active basement landslide at Mount Etna (Italy)

摘要

The flanks of volcanoes may slide in response to the loading of the edifice on a weak basement, magma push,and/or to tectonic stress. However, examples of stratovolcanoes emplaced on active landslides are lackingand the possible effects on the volcano dynamics unknown. Here, we use aeromagnetic data to construct athree-dimensional model of the clay-rich basement of Etna volcano (Italy). We provide evidence for a largestratovolcano growing on a pre-existing basement landslide and show that the eastern Etna flank, whichslides toward the sea irrespective of volcanic activity, moves coherently with the underlying landslide. Thefilling of the landslide depression by lava flows through time allows the formation of a stiffness barrier,which is responsible for the long-term migration of the magma pathways from the coast to the present-dayEtna summit. These unexpected results provide a new interpretation clue on the causes of the volcanicinstability processes and of the mechanisms of deflection and migration of volcanic conduits.