Experimental study of the interplay between magmatic rift intrusion and flank instability with application to the 2001 Mount Etna eruption

Mount Etna volcano is subject to transient magmatic intrusions and flank movement. The east flank of the edifice, in particular, is moving eastward and is dissected by the Timpe Fault System. The relationship of this eastward motion with intrusions and tectonic fault motion, however, remains poorly constrained. Here we explore this relationship by using analogue experiments that are designed to simulate magmatic rift intrusion, flank movement, and fault activity before, during, and after a magmatic intrusion episode. Using particle image velocimetry allows for a precise temporal and spatial analysis of the development and activity of fault systems. The results show that the occurrence of rift intrusion episodes has a direct effect on fault activity. In such a situation, fault activity may occur or may be hindered, depending on the interplay of fault displacement and flank acceleration in response to dike intrusion. Our results demonstrate that a complex interplay may exist between an active tectonic fault system and magmatically induced flank instability. Episodes of magmatic intrusion change the intensity pattern of horizontal flank displacements and may hinder or activate associated faults. We further compare our results with the GPS data of the Mount Etna 2001 eruption and intrusion. We find that syneruptive displacement rates at the Timpe Fault System have differed from the preeruptive or posteruptive periods, which shows a good agreement of both the experimental and the GPS data. Therefore, understanding the flank instability and flank stability at Mount Etna requires consideration of both tectonic and magmatic forcing.