Where does a volcano break? Using self-potential reiteration to forecast the precise location of major destructive events on active volcanoes: the case study of the Piton de la Fournaise 2007 caldera collapse

The Dolomieu caldera collapse (April 2007) was one of the most outstanding events of recent decades at Piton de la Fournaisevolcano. Forecasting such a destructive event is difficult but since then, the development of tools and monitoring networks has improved our knowledge of the dynamics of volcano instability. However, the precise location of volcano failure remains hard to constrain. Here, we show that reiteration of self-potential (SP) measurements along a profile prior to caldera collapse brings valuable insights on the most instable areas around the Dolomieu crater, revealing information not visible on one single SP acquisition. In particular, the SP dynamic highlights the presence of low cohesion/low strength materials at depth despite a lack of surface expression. Our data show that preferential failure area can be precisely identified at the meter scale, highlighting the relevance of SP reiteration as a tool for locating instabilities in both volcanic and non-volcanic environments.