Biased Volcanic Hazard Assessment Due to Incomplete Eruption Records on Ocean Islands: An Example of Sete Cidades Volcano, Azores

Kueppers, Ulrich; Pimentel, Adriano; Ellis, Ben; Forni, Francesca; Neukampf, Julia; Pacheco, José; Perugini, Diego; Queiroz, G.

doi:10.3389/feart.2019.00122

Cited by 14 publications

(16 citation statements)

References 52 publications

(115 reference statements)

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“…Nevertheless, the volume of erupted magma estimated for the Lajes Ignimbrite (0.31-0.42 km 3 DRE) is within the same order of magnitude of other major explosive eruptions recorded in the Azores, such as the 4.6 ka Fogo A Plinian eruption (Fogo volcano, São Miguel) with 0.64 km 3 DRE (Booth et al, 1978) and the 16 ka Santa Bárbara caldera-forming eruption (Sete Cidades volcano, São Miguel) with 0.25-0.54 km 3 DRE (Kueppers et al, 2019). However, these differ from the Lajes Ignimbrite-forming eruption as they produced thick pumice fall deposits in addition to ignimbrites (Pensa et al, 2015;Queiroz et al, 2015).…”

Section: Ignimbrite Aspect Ratio and Volumesupporting

confidence: 71%

Eruption Style, Emplacement Dynamics and Geometry of Peralkaline Ignimbrites: Insights From the Lajes-Angra Ignimbrite Formation, Terceira Island, Azores

et al. 2021

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Ignimbrites are relatively uncommon on ocean island volcanoes and yet they constitute a significant portion of the stratigraphy of Terceira Island (Azores). The Lajes-Angra Ignimbrite Formation (ca. 25 cal ka BP) contains the youngest ignimbrites on Terceira and records two ignimbrite-forming eruptions of Pico Alto volcano that occurred closely spaced in time. Here, we present the first detailed lithofacies analysis and architecture of the Angra and Lajes ignimbrites, complemented by petrographic, mineral chemical, whole rock and groundmass glass geochemical data. The two ignimbrites have the same comenditic trachyte composition, but show considerable variability in trace element and groundmass glass compositions, revealing complex petrogenetic processes in the Pico Alto magma reservoir prior to eruption. The Angra Ignimbrite has a high-aspect ratio and is massive throughout its thickness. It was formed by a small-volume but sustained pyroclastic density current (PDC) fed by a short-lived, low pyroclastic fountain. Overall, the PDC had high particle concentration, granular fluid-based flow conditions and was mostly channelled into a valley on the south part of Terceira. By contrast, the Lajes Ignimbrite has a low-aspect ratio and shows vertical and lateral lithofacies variations. It was formed by a sustained quasi-steady PDC generated from vigorous and prolonged pyroclastic fountaining. The ignimbrite architecture reveals that depositional conditions of the parent PDC evolved as the eruption waxed. The dilute front of the current rapidly changed to a high particle concentration, granular fluid-based PDC that extended to the north and south coasts, with limited capacity to surmount topographic highs. Contrary to what is commonly assumed, the low-aspect ratio of the Lajes Ignimbrite is interpreted to result from deposition of a relatively low velocity PDC over a generally flat topography. This work highlights that the geometry (aspect ratio) of ignimbrites does not necessarily reflect the kinetic energy of PDCs and thus should not be used as a proxy for PDC emplacement dynamics. Although the probability of an ignimbrite-forming eruption on Terceira is relatively low, such a scenario should not be underestimated, as a future event would have devastating consequences for the island’s 55,000 inhabitants.

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Section: Ignimbrite Aspect Ratio and Volumesupporting

confidence: 71%

Eruption Style, Emplacement Dynamics and Geometry of Peralkaline Ignimbrites: Insights From the Lajes-Angra Ignimbrite Formation, Terceira Island, Azores

et al. 2021

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“…Simulations of PDCs were performed with the energy cone model (Malin and Sheridan, 1982), which provides a fast and conservative approach to assessing the maximum potential extent of these volcanic products (e.g. Alberico et al, 2002Alberico et al, , 2008Felpeto et al, 2007;Toyos et al, 2007).…”

Section: Pyroclastic Density Currentsmentioning

confidence: 99%

“…Explosive eruptions can affect large areas of land, ocean and airspace, threatening people, animals, buildings, infrastructure, transportation, communications, agriculture land and water resources (e.g. Guffanti et al, 2005;Spence et al, 2005;Wilson et al, 2012;Scaini et al, 2014;Wilson et al, 2014;Craig et al, 2016;Brown et al, 2017;Kueppers et al, 2019). In more extreme cases, explosive eruptions may also affect global climate (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Oceanic islands are particularly vulnerable to volcanic eruptions and other geological hazards due to their typical remote location, small size and rough topography, which, combined with high population densities and weak economies, make risk management and evacuation very challenging (e.g. Pelling and Uitto, 2001;Clare et al, 2018;Kueppers et al, 2019;Pimentel et al, 2020). The Azores islands (North Atlantic Ocean) have an extensive geological record of explosive volcanic eruptions that typically occur at trachytic central volcanoes (Pimentel et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the impact of explosive eruptions of Fogo volcano (São Miguel, Azores) on the tourism economy

Medeiros¹,

Carmo²,

Pimentel³

et al. 2021

Nat. Hazards Earth Syst. Sci.

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Abstract. The Azores are an active volcanic region that offers exceptional conditions for nature-based tourism, one of the main axes of economic growth in the archipelago. A future volcanic eruption may have long-term consequences to this economic sector. Therefore, it is fundamental to assess its vulnerability to volcanic hazards in order to try to mitigate the associated risk. This study proposes a new approach to assessing the economic impact of explosive eruptions on the tourism sector. We considered two eruptive scenarios for Fogo volcano (São Miguel Island), the most probable (Volcanic Explosivity Index, VEI, 4 sub-Plinian eruption) and the worst-case (VEI 5 Plinian eruption), both producing tephra fallout and pyroclastic density currents. The results of numerical simulations were overlaid with tourism-related buildings and infrastructure of Vila Franca do Campo municipality to identify the elements at risk. The loss present value method was used to estimate the benefits generated by the accommodation units over 30 years for different economic scenarios. The assessment of the economic impact using 2018 indicators reveals that in a near-total-destruction scenario, the economic loss is approximately EUR 145 million (considering a 2 % discount rate). This approach can also be applied to other volcanic regions, geologic hazards and economic sectors.

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“…Explosive eruptions can affect large areas of land, ocean, and airspace, threatening people, animals, buildings, infrastructure, transportation, communications, agriculture land, and water resources (e.g. Guffanti et al, 2005;Spence et al, 2005;Wilson et al, 2012;Scaini et al, 2014;Wilson et al, 2014;Craig et al, 2016;Brown et al, 2017;Kueppers et al, 2019). In more extreme cases, explosive eruptions may also affect global climate (e.g.…”

Section: Introductionmentioning

confidence: 99%

Assessing the impact of explosive eruptions of Fogo volcano (São Miguel, Azores) on the tourism economy

Medeiros¹,

Carmo²,

Pimentel³

et al. 2020

Preprint

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Abstract. The Azores is an active volcanic region that offers exceptional conditions for nature-based tourism, one of the main axes of economic growth in this region. A future volcanic eruption in the archipelago may have long-term consequences to this economic sector. Therefore, it is fundamental to assess its vulnerability to volcanic hazards in order to try to mitigate the associated risk. This study proposes a new approach to assess the economic impact of explosive eruptions on the tourism sector. We considered two eruptive scenarios for Fogo volcano (São Miguel Island), the most probable (VEI 4 sub-Plinian eruption) and the worst-case (VEI 5 Plinian eruption), both producing tephra fallout and PDCs. The results of numerical simulations were overlaid with tourism-related buildings and infrastructure of Vila Franca do Campo municipality to identify the elements at risk. The Loss Present Value method was used to estimate the benefits generated by the accommodation units over 30 years for different economic scenarios. The assessment of the economic impact using 2018 indicators reveals that in a near total destruction scenario the economic loss is approximately 145 million euros. Such approach can also be adopted to other volcanic regions, other geologic hazards and other economic sectors.

show abstract

Biased Volcanic Hazard Assessment Due to Incomplete Eruption Records on Ocean Islands: An Example of Sete Cidades Volcano, Azores

Cited by 14 publications

References 52 publications

Eruption Style, Emplacement Dynamics and Geometry of Peralkaline Ignimbrites: Insights From the Lajes-Angra Ignimbrite Formation, Terceira Island, Azores

Eruption Style, Emplacement Dynamics and Geometry of Peralkaline Ignimbrites: Insights From the Lajes-Angra Ignimbrite Formation, Terceira Island, Azores

Assessing the impact of explosive eruptions of Fogo volcano (São Miguel, Azores) on the tourism economy

Assessing the impact of explosive eruptions of Fogo volcano (São Miguel, Azores) on the tourism economy

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