Reappraisal of gap analysis for effusive crises at Piton de la Fournaise

Abstract

Effective and rapid effusive crisis response is necessary to mitigate the risks associated with lava flows that could threaten or inundate inhabited or visited areas. At Piton de la Fournaise (La Réunion, France), well-established protocols between Observatoire Volcanologique du Piton de la Fournaise – Institut de Physique du Globe de Paris (OVPF-IPGP) and civil protection, and between scientists of a multinational array of institutes, allow effective tracking of eruptive crises and hazard management embracing all stakeholders. To assess the outstanding needs for such responses Tsang and Lindsay (J Appl Volcanol 9:9, 2020) applied a gap analysis to assess research gaps in terms of preparedness, response and recovery at 11 effusive centers, including Piton de la Fournaise. For Piton de la Fournaise, their gap analysis implied widespread gaps in the state of knowledge. However, their work relied on incomplete and erroneous data and methods, resulting in a gap analysis that significantly underrepresented this state of knowledge. We thus here re-build a correct database for Piton de la Fournaise, properly define the scope of an appropriate gap analysis, and provide a robust gap analysis, finding that there are, actually, very few gaps for Piton de la Fournaise. This is a result of the existence of a great quantity of published work in the peer-reviewed literature, as well as frequent reports documenting event impact in the local press and observatory reports. At Piton de la Fournaise, this latter (observatory-based) resource is largely due to the efforts of OVPF-IPGP who have a wealth of experience having responded to 81 eruptions since its creation in 1979 through the end of September 2021.Although welcome and necessary, especially if it is made by a group of scientists outside the local management of the volcanic risk (i.e., a neutral group), such gap analysis need to be sure to fully consider all available peer-reviewed literature, as well as newspaper reports, observatory releases and non-peer-reviewed eruption reports, so as to be complete and correct. Fundamentally, such an analysis needs to consider the information collected and produced by the volcano observatory charged with handling surveillance operations and reporting duties to civil protection for the volcano under analysis. As a very minimum, to ensure that a necessarily comprehensive and complete treatment of the scientific literature has been completed, we recommend that a third party expert, who is a recognized specialist in terms of research at the site considered, reviews and checks the material used for the gap analysis before final release of recommendations.

Structured elicitation of expert judgement in real-time eruption scenarios

“…The creation of OVPF-IPGP was the direct result of the 1977 eruption of Piton de la Fournaise during which lava flows entered the town of Piton Sainte Rose (see Figure 1A). Today, OVPF-IPGP manages monitoring and civil protection reporting duties for volcanic and seismic hazard on La Réunion [Peltier et al 2022]. Most of the historical activity of Piton de la Fournaise has been confined to the unpopulated Enclos Fouqué caldera [Figure 1A; Harris et al 2017].…”

“…Indeed a gap analysis for effusive crisis response completed by OVPF-IPGP revealed that, whereas knowledge and published experience of hazard, risk and losses during "normal" effusive crises within the caldera is excellent, as well as monitoring, mitigation, and recovery efforts in those circumstances, there is a gap for "Hors Enclos" events (i.e. those occurring beyond the caldera) [Peltier et al 2022].…”

“…This network allows OVPF-IPGP to provide early warning for eruptive activity, to track on-going activity [e.g. Peltier et al 2021] and to provide the authorities with notice of any change in activity [Peltier et al 2022]. Indeed, through the government-mandated emergency plan (Organisation de la Réponse de Sécurité Civile (ORSEC) -Volcan http://volcano.si.edu/search_volcano.cfm du Piton de la Fournaise) OVPF-IPGP must inform the civil protection department of the Préfecture (i.e.…”

“…the decentralized administrative service of the French government) of any changes in volcanic activity so that the authorities can change alert levels accordingly. These alert levels (currently under review) are [Peltier et al 2022 In the case of Alerts 2.1 and 2.2, visitor access to the Enclos Fouqué caldera is closed, and in the event of Alert 2.3 all population centers under threat are evacuated. Over the last 100 years, eruptive fissures have opened only three times outside of the Enclos Fouqué caldera : in 1977, 1986, and 1998.…”

“…Over the last 100 years, eruptive fissures have opened only three times outside of the Enclos Fouqué caldera : in 1977, 1986, and 1998. Lava flows reached populated areas only in 1977 and 1986; no casualties were reported, but a few dozen houses and infrastructure were destroyed [Peltier et al 2022]. Thus, apart from the 1986 eruption, OVPF-IPGP and the Préfecture have dealt only with eruptions that have not reached populated areas (since it was established in 1979).…”