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Long-term probabilistic volcanic hazard assessment on islands: the case of tephra fallout at São Miguel airport (Azores archipelago)

Simone Aguiar1 , Laura Sandri2, Adriano Pimentel1, José Pacheco1

  • Affiliations: 1Research Institute for Volcanology and Risk Assessment (IVAR) from University of the Azores, Ponta Delgada, Portugal; 2Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Bologna, Italia

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 55

  • Programme No: 6.3.14

  • Theme 6 > Session 3

Abstract

Volcanic islands face unique challenges when affected by explosive eruptions due to their limited land area, typical rough topography, and the concentration of populated areas and infrastructure close to volcanic centres. Moreover, eruption records of island volcanoes are often incomplete or poorly preserved, generating large uncertainties in their eruptive behaviour and in constraining eruption source parameters.  This study presents a long-term probabilistic volcanic hazard assessment (PVHA) methodology applied to a volcanic island, specifically focusing on the airport of São Miguel Island (137,000 inhabitants) as a case study. It aims to evaluate the potential impacts of tephra fallout on airport operations and infrastructure, providing the probability of different tephra loads impacting this critical infrastructure over specific time windows.  To perform this analysis, different sources of information were integrated, including the probability of an explosive trachytic eruption at each of the three central volcanoes on the island, as well as the likely locations to host future vents. Probabilistic simulations of tephra deposition were conducted for different eruption scenarios accounting for wind variability. Bayesian Event Trees were constructed for each volcano to produce hazard curves to quantify tephra load exceedance probabilities at the airport location, and probability maps showing the exceedance probability of specific tephra load thresholds. This approach represents a methodology for volcanic hazard assessment on islands, suitable for application to other volcanic regions facing similar challenges as the Azores, thus supporting effective risk management and enhancing community resilience.