Because of their continuous and relatively rapid growth, volcanoes are inherently unstable, with instabilities ranging from slow volcano spreading to sudden flank collapse. Instability may induce magma ascent and eruption, mainly through dikes, to such an extent that it may significantly control the evolution of volcanic edifices and their associated hazards. Understanding what controls the development of the instability of a volcanic edifice is therefore crucial for hazard assessment and mitigation.
For example, what are the hazards associated with volcanic flank instability, and under what conditions do these hazards occur? What can we learn about flank motion by studying an unstable volcano? Addressing these questions is the goal of the Etna Flank project, which, after 2 years, has provided constraints on the characteristics and hazards of volcano instability at Italy's Mount Etna.