Long-term multi-hazard assessment for El Misti volcano (Peru)

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• 作者：Laura Sandri (1)
  Jean-Claude Thouret (2)
  Robert Constantinescu (3)
  Sébastien Biass (4)
  Roberto Tonini (1)
  
• 关键词：BET_VH ; TITAN2D ; TEPHRA2 ; Probabilistic volcanic hazard ; Multi ; hazard assessment ; El Misti ; Arequipa
• 刊名：Bulletin of Volcanology
• 出版年：2014
• 出版时间：February 2014
• 年：2014
• 卷：76
• 期：2
• 全文大小：2,117 KB
• 作者单位：Laura Sandri (1)
  Jean-Claude Thouret (2)
  Robert Constantinescu (3)
  Sébastien Biass (4)
  Roberto Tonini (1)
  
  1. Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, via Donato Creti, 12, 40128, Bologna, Italy
  2. PRES Clermont, Université Blaise Pascal, Laboratoire Magmas et Volcans, UMR6524 CNRS, IRD-R163, CLERVOLC, 5 rue Kessler, 63038, Clermont-Ferrand cedex, France
  3. Faculty of Geography, Babe?-Bolyai University, Clinicilor 5-7, 400006, Cluj-Napoca, Romania
  4. Section des sciences de la Terre et de l’environnement, Université de Genève, Rue des Mara?chers 13, Geneva, Switzerland
  
• ISSN：1432-0819

文摘

We propose a long-term probabilistic multi-hazard assessment for El Misti Volcano, a composite cone located <20?km from Arequipa. The second largest Peruvian city is a rapidly expanding economic centre and is classified by UNESCO as World Heritage. We apply the Bayesian Event Tree code for Volcanic Hazard (BET_VH) to produce probabilistic hazard maps for the predominant volcanic phenomena that may affect c.900,000 people living around the volcano. The methodology accounts for the natural variability displayed by volcanoes in their eruptive behaviour, such as different types/sizes of eruptions and possible vent locations. For this purpose, we treat probabilistically several model runs for some of the main hazardous phenomena (lahars, pyroclastic density currents (PDCs), tephra fall and ballistic ejecta) and data from past eruptions at El Misti (tephra fall, PDCs and lahars) and at other volcanoes (PDCs). The hazard maps, although neglecting possible interactions among phenomena or cascade effects, have been produced with a homogeneous method and refer to a common time window of 1?year. The probability maps reveal that only the north and east suburbs of Arequipa are exposed to all volcanic threats except for ballistic ejecta, which are limited to the uninhabited but touristic summit cone. The probability for pyroclastic density currents reaching recently expanding urban areas and the city along ravines is around 0.05?%/year, similar to the probability obtained for roof-critical tephra loading during the rainy season. Lahars represent by far the most probable threat (around 10?%/year) because at least four radial drainage channels can convey them approximately 20?km away from the volcano across the entire city area in heavy rain episodes, even without eruption. The Río Chili Valley represents the major concern to city safety owing to the probable cascading effect of combined threats: PDCs and rockslides, dammed lake break-outs and subsequent lahars or floods. Although this study does not intend to replace the current El Misti hazard map, the quantitative results of this probabilistic multi-hazard assessment can be incorporated into a multi-risk analysis, to support decision makers in any future improvement of the current hazard evaluation, such as further land-use planning and possible emergency management.