The volcanic risk assesses the threat of the active volcanoes near the site: lava flows, pyroclastic flows and lahars, which reach about 100 km from the vent. It uses the ThinkHazard! hazard levels (World Bank, GFDRR) on the volcanoes of the Global Volcano Model, and the Volcano Hazard Index (VHI) of Brown et al. 2015 to single out the most dangerous volcanoes. It does not depend on the climate scenarios; ash fall far from the volcano is not in the class.
Indicator. Hazard level of the most dangerous volcano within 100 km of the site.
Data. Holocene volcanoes of the Global Volcano Model (GVM/IAVCEI, contribution to the UN GAR 2015): position, largest Holocene VEI and Volcano Hazard Index level (VHI, Brown et al. 2015, for 328 volcanoes); eruptions of the Smithsonian Global Volcanism Program (VEI and date). Static value, the same for every scenario and year.
Calculation. ThinkHazard! rule (GFDRR, methodology report v2.0):
(1) For each volcano the level comes from the largest known VEI: high with VEI 5 or more, medium with VEI 3-4, low below 3; without a VEI from the last eruption: high if in the Common Era, medium if in the Holocene, low if older or none.
(2) The level applies within 100 km of the volcano, the maximum reach of lava, pyroclastic flows and lahars.
(3) The site takes the highest level of the volcanoes within 100 km.
Thresholds → level A–F.
• A: no volcano within 100 km (very low)
• B: low level
• C: medium level; D if the volcano is in level III of the VHI
• E: high level; F if the volcano is in level III of the VHI.
Splitting medium and high with the VHI is an xNatura choice on the two published sources. Ash fall far from the volcano is not in the class, as in ThinkHazard!.
From physical to impact. The physical level (A–F) is combined with the production process's sensitivity through the risk matrix (6 physical levels by 5 sensitivity bands) → impact level. Version 2025 also turned the impact level into a value at risk with a damage factor per class, an xNatura estimate without a published source: it is no longer used.
Economic damage. Version 2026, xNatura estimate: 0 €, until the global probabilistic ash fall maps of the Global Volcano Model (Jenkins et al. 2015) arrive, already requested from the authors; with them the loss of roofs under the ash load will be calculated. Today probabilistic maps exist only for some regions (40 volcanoes in Indonesia and the Philippines, Jenkins et al. 2022; Vesuvius, Campi Flegrei and Ischia, Massaro et al. 2023).
Sources.
• [ThinkHazard! methodology report (GFDRR)](ThinkHazard! methodology report (GFDRR))
• [Brown et al. 2015, Global volcanic hazard and risk (GVM)](Brown et al. 2015, Global volcanic hazard and risk (GVM))
• [Smithsonian Institution Global Volcanism Program](Smithsonian Institution Global Volcanism Program)
• [The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism](The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism)
• [Jenkins et al. 2022, Evaluating and ranking Southeast Asia's exposure to explosive volcanic hazards](Jenkins et al. 2022, Evaluating and ranking Southeast Asia's exposure to explosive volcanic hazards)
• [Massaro et al. 2023, Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes](Massaro et al. 2023, Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes)
• [Blong et al. 2017, Estimating building vulnerability to volcanic ash fall for insurance and other purposes](Blong et al. 2017, Estimating building vulnerability to volcanic ash fall for insurance and other purposes).
Indicator. Hazard level of the most dangerous volcano within 100 km of the site.
Data. Holocene volcanoes of the Global Volcano Model (GVM/IAVCEI, contribution to the UN GAR 2015): position, largest Holocene VEI and Volcano Hazard Index level (VHI, Brown et al. 2015, for 328 volcanoes); eruptions of the Smithsonian Global Volcanism Program (VEI and date). Static value, the same for every scenario and year.
Calculation. ThinkHazard! rule (GFDRR, methodology report v2.0):
(1) For each volcano the level comes from the largest known VEI: high with VEI 5 or more, medium with VEI 3-4, low below 3; without a VEI from the last eruption: high if in the Common Era, medium if in the Holocene, low if older or none.
(2) The level applies within 100 km of the volcano, the maximum reach of lava, pyroclastic flows and lahars.
(3) The site takes the highest level of the volcanoes within 100 km.
Thresholds → level A–F.
• A: no volcano within 100 km (very low)
• B: low level
• C: medium level; D if the volcano is in level III of the VHI
• E: high level; F if the volcano is in level III of the VHI.
Splitting medium and high with the VHI is an xNatura choice on the two published sources. Ash fall far from the volcano is not in the class, as in ThinkHazard!.
From physical to impact. The physical level (A–F) is combined with the production process's sensitivity through the risk matrix (6 physical levels by 5 sensitivity bands) → impact level. Version 2025 also turned the impact level into a value at risk with a damage factor per class, an xNatura estimate without a published source: it is no longer used.
Economic damage. Version 2026, xNatura estimate: 0 €, until the global probabilistic ash fall maps of the Global Volcano Model (Jenkins et al. 2015) arrive, already requested from the authors; with them the loss of roofs under the ash load will be calculated. Today probabilistic maps exist only for some regions (40 volcanoes in Indonesia and the Philippines, Jenkins et al. 2022; Vesuvius, Campi Flegrei and Ischia, Massaro et al. 2023).
Sources.
• [ThinkHazard! methodology report (GFDRR)](ThinkHazard! methodology report (GFDRR))
• [Brown et al. 2015, Global volcanic hazard and risk (GVM)](Brown et al. 2015, Global volcanic hazard and risk (GVM))
• [Smithsonian Institution Global Volcanism Program](Smithsonian Institution Global Volcanism Program)
• [The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism](The volcanic explosivity index (VEI) an estimate of explosive magnitude for historical volcanism)
• [Jenkins et al. 2022, Evaluating and ranking Southeast Asia's exposure to explosive volcanic hazards](Jenkins et al. 2022, Evaluating and ranking Southeast Asia's exposure to explosive volcanic hazards)
• [Massaro et al. 2023, Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes](Massaro et al. 2023, Assessing long-term tephra fallout hazard in southern Italy from Neapolitan volcanoes)
• [Blong et al. 2017, Estimating building vulnerability to volcanic ash fall for insurance and other purposes](Blong et al. 2017, Estimating building vulnerability to volcanic ash fall for insurance and other purposes).