Aravena A. auteur aut IRD Tadini A. auteur aut IRD Bevilacqua A. auteur aut IRD Samaniego Pablo auteur aut IRD Bernard B. auteur aut IRD Hidalgo S. auteur aut IRD Le Pennec Jean-Luc auteur aut IRD Martínez-Yáñez P. auteur aut IRD García J. auteur aut IRD Roche Olivier auteur aut IRD text journalArticle eng text/pdf reformatted digital access We assess the volcanic hazard posed by pyroclastic density currents (PDCs) at Tungurahua volcano, Ecuador, using a probabilistic approach based on the analysis of calibrated numerical simulations. We address the expected variability of explosive eruptions at Tungurahua volcano by adopting a scenario-based strategy, where we consider three cases: violent Strombolian to Vulcanian eruption (VEI 2), sub-Plinian eruption (VEI 3), and sub-Plinian to Plinian eruption (VEI 4-5). PDCs are modeled using the branching energy cone model and the branching box model, considering reproducible calibration procedures based on the geological record of Tungurahua volcano. The use of different calibration procedures and reference PDC deposits allows us to define uncertainty ranges for the inundation probability of each scenario. Numerical results indicate that PDCs at Tungurahua volcano propagate preferentially toward W and NW, where a series of catchment ravines can be recognized. Two additional valleys of channelization are observed in the N and NE flanks of the volcano, which may affect the city of Ba & ntilde;os. The mean inundation probability calculated for Ba & ntilde;os is small (6 +/- 3%) for PDCs similar to those emplaced during recent VEI 2 eruptions (July 2006, February 2008, May 2010, July 2013, February 2014, and February 2016), and on the order of 13 +/- 4% for a PDC similar to that produced during the sub-Plinian phase of the August 2006 eruption (VEI 3). The highest intensity scenario (VEI 4-5), for which we present and implement a novel calibration procedure based on a few control points, produces inundation areas that nearly always include inhabited centers such as Ba & ntilde;os, Puela, and Cotal & oacute;, among others. This calibration method is well suited for eruptive scenarios that lack detailed field information, and could be replicated for poorly known active volcanoes around the world. specialized Hazard assessment Pyroclastic density currents Tungurahua volcano EQUATEUR 066 064 86 10 84 [18 p.] 2024 0258-8900 https://www.documentation.ird.fr/hor/fdi:010091381 10.1007/s00445-024-01768-y 0258-8900 [F B010091381] https://www.documentation.ird.fr/hor/fdi:010091381 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2024-11/010091381.pdf IRD - Base Horizon / Pleins textes 2024-11-13 2025-11-06 fdi:010091381 fre