University of South Florida Scholar Commons School of Geosciences Faculty and Staff Publications School of Geosciences 7-2020 Dynamics and Impacts of the May 8th, 1902 Pyroclastic Current at Mount Pelée (Martinique): New Insights From Numerical Modeling Valentin Gueugneau University of South Florida, [email protected] Karim Kelfoun Université Clermont Auvergne Sylvain J. Charbonnier University of South Florida, [email protected] Aurelie Germa University of South Florida, [email protected] Guillaume Carazzo Université de Paris Follow this and additional works at: https://scholarcommons.usf.edu/geo_facpub Part of the Earth Sciences Commons Scholar Commons Citation Gueugneau, Valentin; Kelfoun, Karim; Charbonnier, Sylvain J.; Germa, Aurelie; and Carazzo, Guillaume, "Dynamics and Impacts of the May 8th, 1902 Pyroclastic Current at Mount Pelée (Martinique): New Insights From Numerical Modeling" (2020). 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For more information, please contact [email protected]. feart-08-00279 July 20, 2020 Time: 12:14 # 1 ORIGINAL RESEARCH published: 22 July 2020 doi: 10.3389/feart.2020.00279 Dynamics and Impacts of the May 8th, 1902 Pyroclastic Current at Mount Pelée (Martinique): New Insights From Numerical Modeling Valentin Gueugneau1,2*, Karim Kelfoun2, Sylvain Charbonnier1, Aurelie Germa1 and Guillaume Carazzo3 1 School of Geosciences, University of South Florida, Tampa, FL, United States, 2 Université Clermont Auvergne, Centre National de la Recherche Scientique (CNRS), Institut de Recherche Pour le Developpement (IRD), Observatoire de Physique du Globe de Clermont (OPGC), Laboratoire Magmas et Volcans, Clermont-Ferrand, France, 3 Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, France The Mount Pelée May 8th, 1902 eruption is responsible for the deaths of more than 29,000 people, as well as the nearly-complete destruction of the city of Saint Pierre by a single pyroclastic current, and is, sadly, the deadliest eruption of the 20th century. Despite intensive field studies on the associated deposit, two conflicting interpretations Edited by: of the pyroclastic current dynamics (either a blast or a simple ash-cloud surge) emerged Andrea Bevilacqua, in the 90’s and have been paralyzing research ever since, leaving numerous unknowns National Institute of Geophysics and Volcanology (INGV), Italy (i.e., source conditions, volume). This study is the first to investigate numerically the Reviewed by: May 8th, 1902 pyroclastic current, using the new two-phase version of VolcFlow that E. Bruce Pitman, simulates more accurately both parts of pyroclastic currents (i.e., the block-and-ash University at Buffalo, United States Michael Manga, flow and the ash-cloud surge). Physical flow parameters are either extracted from field University of California, Berkeley, data or estimated empirically when no value was found in the literature. Among the two United States interpretations, only the simple ash-cloud surge is tested, generated from a block-and- *Correspondence: ash flow initially supplied from the artificially recreated 1902 crater. The block-and-ash Valentin Gueugneau [email protected] flow overflows from the southern V-shaped crater outlet and stays confined into the Rivière Blanche, whereas the ash-cloud surge expands radially and spreads westward, Specialty section: seaward, and eastward, ultimately reaching St Pierre 8 km away, within 330 s. The This article was submitted to Volcanology, extent of both parts of the simulated current, as well as the thickness and the direction a section of the journal of the ash-cloud surge are accurately reproduced for a total volume of 32 × 106 m3, for Frontiers in Earth Science which a significant part (one third) is deposited in the sea (not recorded in previous Received: 17 April 2020 Accepted: 17 June 2020 studies). Simulations demonstrate that the pear-like shape of the ash-cloud surge Published: 22 July 2020 deposit is explained by a late surge production along the Rivière Blanche but also that Citation: a blast-like event may be required at the initial stage of the explosion, which in some Gueugneau V, Kelfoun K, way reconciles the two conflicting past interpretations. Results also highlight the role Charbonnier S, Germa A and Carazzo G (2020) Dynamics played by the topography in controlling transport and deposition mechanisms of such and Impacts of the May 8th, 1902 pyroclastic currents especially the lateral spreading of the ash-cloud surge. Our study Pyroclastic Current at Mount Pelée (Martinique): New Insights From improves the assessment of pyroclastic current-related hazards at Mount Pelée, which Numerical Modeling. could be helpful for future eruptions. Front. Earth Sci. 8:279. doi: 10.3389/feart.2020.00279 Keywords: Mount Pelée, pyroclastic current, numerical modeling, simulation, surge, blast Frontiers in Earth Science | www.frontiersin.org 1 July 2020 | Volume 8 | Article 279 feart-08-00279 July 20, 2020 Time: 12:14 # 2 Gueugneau et al. 1902 Mount Pelée Eruption Simulation INTRODUCTION typical deposit stratigraphy in three layers – unit A, consisting of a mixture of accidental material (substratum rocks, vegetation The 1902–1905 Mount Pelée eruption is a classic example often fragments,:::) eroded from the passage of the blast; unit B, fine- cited by volcanologists and media to demonstrate the hazards depleted layer, composed of coarse particles (few millimeters caused by the generation and rapid emplacement of a violent and to few centimeters); unit C, laminated, composed of lapilli and unpredicted pyroclastic current. On May 8th, 1902, a powerful ash – together with a debris avalanche deposit, (ii) a broad area “nuée ardente” (term used by Lacroix, 1904 to describe the of inundation with substantial damage due to high dynamic pyroclastic current) coming from the crater traveled down the pressures, (iii) evidence of intense erosion at the base of the volcano and nearly destroyed the city of Saint Pierre, 8 km blast deposit sequence, and (iv) extreme velocities (>100 m away. On May 20th, a second powerful pyroclastic current s−1). Recent numerical modeling of the Soufrière Hills Volcano occurred in the same area and achieved the total destruction of (Esposti Ongaro et al., 2008) and Mount St Helens blasts (Esposti St Pierre. The two events were responsible for at least 29,000 Ongaro et al., 2012) show that the dynamics seem to be composed deaths (Lacroix, 1904), culminating in the deadliest volcanic of three main phases: a short burst phase at the beginning eruption of the last century. As such, past studies have mainly during which the magma is fragmented and transported by focused on reconstructing the eruptive sequence in order to better the overpressure of the volcanic gas, a collapse phase during understand the potential hazards of Mount Pelée. One of the first which gravity surpasses the pressure and becomes the driving records of this event was compiled by Lacroix (1904), who arrived force, and a PDC phase in which the flow turns to a pyroclast- on Martinique Island 2 months later and described with great laden density current. Several other eruptions have produced detail the features of the May 8th pyroclastic current (i.e., deposit pyroclastic currents that share some blast criteria including characteristics, damage in St Pierre, and various bodily injuries Mount Unzen in 1991 (Taniguchi and Suzuku-Kamata, 1993), found in the town). Our understanding of the May 1902 Mount Chaitén in 2008 (Major et al., 2013), Arenal in 1968 (Alvarado Pelée pyroclastic currents was improved decades later with et al., 2006), and Merapi in 2010 (Komorowski et al., 2013). the 1980 Mount St Helens eruption (Lipman and Mullineaux, Thus, Komorowski et al. (2013) proposed a modified blast 1981) and the subsequent advances the eruption brought to description of Belousov (2007) by distinguishing three categories the understanding of explosive dome collapse processes. With of blast-like flow: (1) very extensive blasts associated with flank new insight from the St. Helens eruption, numerous studies collapses (Bezymianny, 1956; Mount St. Helens, 1980; Lipman reinterpreted the deposits of the May 1902 eruption (Fisher et al., et al., 1981; Belousov et al., 2007); (2) vertically-directed blasts 1980; Fisher and Heiken, 1982, 1983, 1990; Sparks, 1983; Boudon of intermediate intensity (Lamington, 1951; Taylor, 1958); and and Lajoie, 1989; Bourdier et al., 1989; Charland and Lajoie, (3) low intensity blasts produced by dome collapse (Soufrière 1989; Lajoie et al., 1989; Boudon et al., 1990) to better constrain Hills, 1997; Sparks et al., 2002; Voight et al., 2002; Merapi, 2010; the eruptive source conditions and flow propagation dynamics. Komorowski et al., 2013). With this new description of a volcanic Two conflicting interpretations emerged from these studies: (i) blast, we revisit the May 8th, 1902 eruption at Mount Pelée. St Pierre was destroyed by the ash-cloud surge component of a Since the debate in the early 90s, no consensus has emerged pyroclastic current derived from a primarily block-and-ash flow and consequently some key aspects of the Mt. Pelée eruption (BAF) traveling down the Rivière Blanche (Fisher et al., 1980; remain unclear. The lack of an unambiguous