Osman, S., Crummy, J., Thomas, M. orcid.org/0000-0002-1300-177X et al. (1 more author) (2024) Probabilistic hazard analyses for a small island: methods for quantifying tephra fall hazard and appraising possible impacts on Ascension Island. Bulletin of Volcanology, 86 (10). 82. ISSN 0258-8900
Abstract
Proximal to the source, tephra fall can cause severe disruption, and populations of small volcanically active islands can be particularly susceptible. Volcanic hazard assessments draw on data from past events generated from historical observations and the geological record. However, on small volcanic islands, many eruptive deposits are under-represented or missing due to the bulk of tephra being deposited offshore and high erosion rates from weather and landslides. Ascension Island is such an island located in the South Atlantic, with geological evidence of mafic and felsic explosive volcanism. Limited tephra preservation makes it difficult to correlate explosive eruption deposits and constrains the frequency or magnitude of past eruptions. We therefore combined knowledge from the geological record together with eruptions from the analogous São Miguel island, Azores, to probabilistically model a range of possible future explosive eruption scenarios. We simulated felsic events from a single vent in the east of the island, and, as mafic volcanism has largely occurred from monogenetic vents, we accounted for uncertainty in future vent location by using a grid of equally probable source locations within the areas of most recent eruptive activity. We investigated the hazards and some potential impacts of short-lived explosive events where tephra fall deposits could cause significant damage and our results provide probabilities of tephra fall loads from modelled events exceeding threshold values for potential damage. For basaltic events with 6–10 km plume heights, we found a 50% probability that tephra fallout across the west side of the island would impact roads and the airport during a single explosive event, and if roofs cannot be cleared, three modelled explosive phases produced tephra loads that may be sufficient to cause roof collapse (≥ 100 kg m⁻²). For trachytic events, our results show a 50% probability of loads of 2–12 kg m⁻² for a plume height of 6 km increasing to 898–3167 kg m⁻² for a plume height of 19 km. Our results can assist in raising awareness of the potential impacts of tephra fall from short-lived explosive events on small islands.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. |
Keywords: | Volcanic hazards, Ascension Island, Tephra fall impacts, Built environment, Roof collapse |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Geography (Leeds) > Centre for Spatial Analysis & Policy (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 23 Oct 2024 13:42 |
Last Modified: | 23 Oct 2024 15:57 |
Published Version: | https://link.springer.com/article/10.1007/s00445-0... |
Status: | Published |
Publisher: | Springer |
Identification Number: | 10.1007/s00445-024-01771-3 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:218749 |