Structured elicitation of expert judgement in real-time eruption scenarios: an exercise for Piton de la Fournaise volcano, La Réunion island
Formalised elicitation of expert judgements has been used to help tackle several problematic societal issues, including volcanic crises and pandemic threats. We present an expert elicitation exercise for Piton de la Fournaise volcano, La Réunion island, held remotely in April 2021. This involved 28 experts from nine countries who considered a hypothetical effusive eruption crisis involving a new vent opening in a high-risk area. The tele-elicitation presented several challenges, but is a promising and workable option for application to future volcanic crises. Our exercise considered an "uncommon" eruptive scenario with a vent outside the present caldera and within inhabited areas, and provided uncertainty ranges for several hazard-related questions for such a scenario (e.g. probability of eruption within a defined timeframe; elapsed time until lava flow reaches a critical location, and other hazard management issues). Our exercise indicated that such a scenario would probably present very different characteristics compared to recent eruptions, and that it is fundamental to include well-prepared expert elicitations in updated civil protection evacuation plans to improve disaster response procedures. ; This work was funded by the Agence National de la Recherche (ANR) through project Lava Advance into Vulnerable Areas (LAVA; ANR program: DS0902 2016; project: ANR-16CE39–0009). This is ANR-LAVA con- tribution n°21. This contribution is part of the European Commis- sion grant EVE (DG ECHO Ref: 826292). J.M. received funding from the IMAGINE ERC Grant No 804162 to support the development of this paper. A.T. was funded by the ClerVolc project - Programme 1 "Detection and characterization of volcanic plumes and ash clouds" funded by the French government 'Laboratory of Excellence' initiative. This is ClerVolc contribution n°532. A.T. was also partially funded by the by the French government IDEX-ISITE initiative 16- IDEX-0001 (CAP 20-25). ; Peer reviewed