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. 2019 Feb 5;9:1449. doi: 10.1038/s41598-019-38595-7

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© The Author(s) 2019

Open Access 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 license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license 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 license, visit http://creativecommons.org/licenses/by/4.0/.

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Ash cloud concentration simulations during Plinian eruptions. The two simulations are produced by the volcanic ash-cloud-dispersal model MOCAGE of the Toulouse VAAC based on the Plinian eruption of Kelut the 13 February, 2014 (Supplementary Information Table 1), using different partitioning coefficients and present-day meteorological data. (a) Simulation of ash dispersion in the atmosphere at Kelut volcano 30 hours after the eruption, using the VAAC-default operational ε value of 5%. (b) Same simulation conditions and scenario, but using the Plinian ε value established in this study at 0.5%. The extent of the No-Fly zone (4 mg/m³ for an ash cloud 500-m thick*) is much larger for the VAAC-default ε, yielding a maximum concentration one order of magnitude higher. *The threshold at 4 mg/m³ was first established by the European Commission after the Eyjafjallajökull 2010 eruption²³. It is now described by EASA (European Aviation Safety Agency) and used in the emergency plan EUR/NAT (EURopean and North ATlantic office) as the “High” contamination level.