Accepted Manuscript Origin of the term nuées ardentes and the 1580 and 1808 eruptions on São Jorge Island, Azores N. Wallenstein, A. Duncan, R. Coutinho, D. Chester PII: S0377-0273(17)30358-X DOI: doi:10.1016/j.jvolgeores.2018.03.022 Reference: VOLGEO 6340 To appear in: Journal of Volcanology and Geothermal Research Received date: 19 June 2017 Revised date: 11 March 2018 Accepted date: 25 March 2018 Please cite this article as: N. Wallenstein, A. Duncan, R. Coutinho, D. Chester , Origin of the term nuées ardentes and the 1580 and 1808 eruptions on São Jorge Island, Azores. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Volgeo(2017), doi:10.1016/j.jvolgeores.2018.03.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT 1 ORIGIN OF THE TERM NUÉES ARDENTES AND THE 1580 AND 1808 ERUPTIONS ON SÃO JORGE ISLAND, AZORES Wallenstein, N.(1) Duncan, A.(2) Coutinho, R.(1) Chester, D.(2,3) (1) Instituto de InvestigaçãoACCEPTED em Vulcanologia e AvaliaçãoMANUSCRIPT de Riscos, Universidade dos Açores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal. ([email protected] [email protected] (2) Department of Geography and Planning, University of Liverpool, Liverpool L69 3BX, UK. ([email protected]) (3) Department of Geography and Environmental Science, Liverpool Hope University, Liverpool L16 9JD, UK. ([email protected]) Corresponding Author: N. Wallenstein ([email protected]) ACCEPTED MANUSCRIPT 2 ABSTRACT In this paper we: provide a brief account of the 1580 and 1808 eruptions on São Jorge in the Azores, which produced Pyroclastic Density Currents (PDCs); discuss the first recorded use of the term nuées ardentes to describe these PDCs; trace how this term was introduced into the scientific literature and discuss its adoption by Alfred Lacroix (1863-1948) to describe the 'glowing clouds' produced by Mt. Pelée (Martinique) in 1902. The 1580 and 1808 eruptions on São Jorge are important because they provide early descriptions of PDCs. Documentary evidence of the eruptions and their impacts suggest that the 1580 PDC was a hotter flow, whereas the 1808 PDCs were cooler and more moist. Contemporary accounts describe the 1580 PDC as a 'globe of fire', mixed with 'caustic smoke' and moving at speed towards the bottom of the slope. In contrast, the 1808 PDCs comprised humid ash, were not incandescent and it is likely that the flows were cooler than that produced in 1580. Since the eruption of Mt. Pelée in 1902, it has been widely accepted that the term nuées ardentes was introduced by Lacroix (1904), being based on his description of the pyroclastic flows that he witnessed. Lacroix acknowledges that the Portuguese expression, ardente nuvem was first used in contemporary accounts of the São Jorge PDCs. This was first translated as nuée ardente and introduced into the scientific by the French geologist Ferdinand Fouqué (1828-1904), who was also Lacroix's father-in-law. Indeed, Lacroix provides an account of the 1580 and 1808 eruptions of São Jorge in his 1904 work La Montagne Pelée et ses Éruptions. The seminal work of Frank Alvord Perret (1867-1943) on the 1929-32 eruptions of Mt. Pelée and his description of nuées ardentes probably helped reinforce the association between the term and Mt. Pelée. ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 3 KEYWORDS Nuées ardentes, São Jorge (Azores), 1580 eruption, 1808 eruption ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 INTRODUCTION 'Pyroclastic density currents are laterally moving buoyantly expanding mixtures of hot gases and fragmental particles (ash, lapilli, blocks and boulders). They were first called nuées ardentes or glowing clouds' (Cole et al., 2015, pp. 944). In many accounts, it is generally accepted (e.g. Rittmann, 1962; Macdonald, 1972; Francis, 1993) that the term was first introduced by Alfred Lacroix (1904) in a description of the catastrophic eruption of Mt. Pelée, Martinique, in 1902. Indeed, Peter Francis states 'It is a little surprising .... that similar phenomena had not been recognised prior to 1902. Since they are not uncommon and must have been observed on many occasions in the past.' (Francis, 1993, pp. 133). This is despite the fact that Lacroix in his seminal work on the Mt. Pelée 1902 eruption states ‘in a note dated April 6 1903, for the first time, I employed the expression nuées ardentes (our italics and translation)’. On return to Paris he learned that such phenomena had been described on São Jorge in the Azores during eruptions of 1580 and 1808 (Lacroix, 1904, pp.170). In this paper we: provide a brief account of these historic Azorean eruptions; discuss the first recorded use of the term nuées ardentes to describe Pyroclastic Density Currents (PDCs); trace how this term was introduced into the scientific literature and discuss its adoption by Lacroix in order to describe the glowing clouds of Mt. Pelée in 1902. THE 1580 AND 1808ACCEPTED ERUPTIONS ON SÃO JORGE MANUSCRIPT Historic Volcanic Activity in the Azores The Azores were uninhabited when first settled by the Portuguese in the mid-15th century and the first historic records of eruptions date from this period. There have been historic eruptions on five of the nine inhabited islands of the Azores archipelago (Fig. 1) on: Faial; Pico; São Jorge; São Miguel and Terceira (Gaspar et al., 2015). In addition, there have ACCEPTED MANUSCRIPT 5 been a number of submarine eruptions the most recent of which is Serreta (1998-2001), being located off the west coast of Terceira. Historic eruptions from the central volcanoes have been trachytic and have included the first observed eruption of Furnas volcano on São Miguel in 1439-43, the final dome forming phase of which was witnessed by the early Portuguese settlers who arrived soon after the main explosive phase of this eruption (Queiroz et al., 1995). The most recent eruption of Furnas occurred in 1630 and was of sub- Plinian dimensions causing around 195 fatalities (Cole et al., 1995; Guest et al., 2015). The largest explosive central eruption in historical times was the 1563 sub-Plinian event of Fogo Volcano, that is also located in São Miguel (Walker and Croasdale, 1971; Booth et al., 1978; Wallenstein et al., 2015). Most eruptions since the 15th century have been both effusive and basaltic and are associated with fissure zones. The 1563 Pico do Sapateiro basaltic eruption occurred at the NW base of Fogo along the line of the Picos Fissural Volcanic System, which is located between Fogo and Sete Cidades central volcanoes on São Miguel. Lava from this eruption reached the north coast of the island. Basaltic fissure eruptions occurred on the island of Pico: in 1562-64, forming the Mistério da Prainha; in 1718 at São João and in 1720, when lava formed the Mistério da Silveira. In the Azores, Mistério (literally, mysteries) is the term used for young, rough and rugged lava terrain (Scarth and Tanguy, 2001, pp. 154). There were also basalticACCEPTED fissure eruptions on the Capelo MANUSCRIPT peninsula of Faial in 1672-73, and on the island of Terceira in 1761 when lava extended towards the north coast causing damage to the village of Biscoitos. Unusual fissure eruptions were: the 1652 eruption in the Picos Fissural Volcanic System of São Miguel, which formed three small trachytic domes (Ferreira et al., 2015); the Santa Luzia flow erupted in 1718 on Pico, that has the appearance of a basaltic aa flow, although the early stage of the eruption was more evolved being ACCEPTED MANUSCRIPT 6 mugearitic in composition (Cappello et al., 2015) and the first phase of the 1761 eruption on Terceira Island, that formed the Mistérios Negros domes which are trachytic (Pimentel et al., 2016). The most significant submarine eruption in historic times was that of Capelinhos on Faial in 1957-58. This was a basaltic Surtseyan eruption that built up a series of cones above sea level and eventually formed an isthmus protruding from the west end of Faial (Anon, 1959; Cole et al., 2001). The phreatomagmatic ash and associated seismic activity of this eruption had a deleterious impact on the people of Faial and their economic activities (Coutinho et al., 2010). The 1580 and 1808 eruptions of São Jorge were basaltic and associated with fissures aligned with the WNW-ESE tectonic trend of the island. The eruptions occurred on the slopes above the coastline between Velas and Urzelina (a distance of around 7 km) on the SW coast of São Jorge (Figs. 1 and 2a). These eruptions were distinct in that, in addition to effusion of basaltic lava, they were associated with phreatomagmatic activity and the generation of PDCs that swept down the steep scarp slopes of the island to the sea (Fouqué, 1873; Madeira, 1998, 2005; França et al., 2010). These PDCs caused fatalities in both eruptions. The 1580 eruption The descriptioACCEPTEDn of the eruption that followsMANUSCRIPT is based on the account by a priest Gaspar Frutuoso (1522-1591). It was published in his multi-volume work, Saudades da Terra which was written in manuscript form between 1586 and 1590, with his account of the 1580 eruption being published three centuries later by Ernesto do Canto (1880, pp. 188-190). Saudades da Terra remained in manuscript form until the late nineteenth century, being published from 1873 onwards (Luz, 1996) and did not become widely available outside ACCEPTED MANUSCRIPT 7 Portugal until well into the Twentieth Century.