Variability of ash deposits at Piton de la Fournaise (La Reunion Island): insights into fragmentation processes at basaltic shield volcanoes

Thivet, Simon; Gurioli, Lucia; Muro, Andréa Di; Eychenne, Julia; Besson, Pascale; Nédélec, Jean-Marie

doi:10.1007/s00445-020-01398-0

Cited by 19 publications

(15 citation statements)

References 91 publications

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“…During the most intense phase of the eruption (i.e., between 5 and 6 April), a significant amount of Pele's hair was emitted. Pele's hair is thin, elongated, and sharp volcanic glass fibers that form during phases of strong degassing and high eruption rate fountaining (Thivet et al, 2020). They are fluid ejections that are stretched during their flight into thin strands (Moune et al, 2007).…”

Section: The Eruptionmentioning

confidence: 99%

Volcano Crisis Management at Piton de la Fournaise (La Réunion) during the COVID-19 Lockdown

Peltier

Ferrazzini

Muro

et al. 2020

Seismological Research Letters

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In March 2020, the coronavirus disease 2019 outbreak was declared a pandemic by the World Health Organization and became a global health crisis. Authorities worldwide implemented lockdowns to restrict travel and social exchanges in a global effort to counter the pandemic. In France, and in French overseas departments, the lockdown was effective from 17 March to 11 May 2020. It was in this context that the 2–6 April 2020 eruption of Piton de la Fournaise (La Réunion Island, Indian Ocean) took place. Upon the announcement of the lockdown in France, a reduced activity plan was set up by the Institut de Physique du Globe de Paris, which manages the Observatoire Volcanologique du Piton de la Fournaise (OVPF). The aim was to (1) maintain remote monitoring operations by teleworking and (2) authorize fieldwork only for critical reasons, such as serious breakdowns of stations or transmission relays. This eruption provided an opportunity for the observatory to validate its capacity to manage a volcanic crisis with 100% remotely operated monitoring networks. We thus present the long- and short-term precursors to the eruption, and the evolution of the eruption recorded using the real-time monitoring data as communicated to the stakeholders. The data were from both continuously recording and transmitting field instruments as well as satellites. The volcano observatory staff remotely managed the volcano crisis with the various stakeholders based only on these remotely functioning networks. Monitoring duties were also assured in the absence of ad hoc field investigation of the eruption by observatory staff or face-to-face communications. The density and reliability of the OVPF networks, combined with satellite observations, allowed for trustworthy instrument-based monitoring of the eruption and continuity of the OVPF duties in issuing regular updates of volcanic activity in the context of a double crisis: volcanic and health.

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Section: The Eruptionmentioning

confidence: 99%

Volcano Crisis Management at Piton de la Fournaise (La Réunion) during the COVID-19 Lockdown

Peltier

Ferrazzini

Muro

et al. 2020

Seismological Research Letters

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“…Thus, in basalts for example, magmatic fragmentation is typically a ductile process in Hawaiian eruptions Thivet et al 2020c), whereas phreatomagmatic fragmentation of the molten fuelcoolant interaction (MFCI) type produces both brittle and ductile particles Zimanowski et al 2015). In contrast, both magmatic and phreatomagmatic fragmentation of rhyolite is typically, though not always ), a brittle process (Austin-Erickson et al 2008;Cashman and Scheu 2015;.…”

Section: Geochemical Analysis (Standard)mentioning

confidence: 99%

“…This is why a coarse ash fraction and, preferably, a medium lapilli fraction, are also studied. Another potential caveat is that certain mildly explosive eruptive styles produce very few fine to extremely fine ash particles so some particles actually found in the 88-63 m (+3.5 to +4ɸ) fraction may represent breakage of larger clasts rather than primary magma fragmentation (Thivet al 2020c).…”

Section: Very Fine Ash Fraction (Standard)mentioning

confidence: 99%

“…Furthermore, many studies were done on unwitnessed eruptions, rather than to document juvenile pyroclast characteristics from an unambiguously known style or fragmentation mechanism. Thus, it is not yet entirely clear how to specifically link juvenile ash characteristics (particle size, morphology, internal features such as crystals and vesicles, surface features, geochemical composition) with specific eruptive styles (Bonadonna et al 2016) or fragmentation processes (Thivet et al 2020c).…”

Section: Introductionmentioning

confidence: 99%

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Standardized analysis of juvenile pyroclasts in comparative studies of primary magma fragmentation; 1. Overview and workflow

et al. 2021

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Juvenile pyroclasts, especially in the ash size range, provide important information on primary fragmentation processes, i.e. initial explosive magma fragmentation, and on the state of the magma both prior to and at the point of fragmentation and quenching. There exists an extensive body of literature focusing on the quantification of juvenile particle morphology (shape), internal textures and surface features spanning several decades, however a standardized method has yet to emerge for comparative studies. No community-wide consensus currently exists (i) regarding the most representative size fraction(s) to be examined, (ii) on sample preparation procedures (such as whether to use whole particle silhouettes or 2D cross-sections), (iii) on imaging techniques and image acquisition parameters, or (iv) on the optimal morphometric parameters to measure. Lack of a standardized method precludes robust comparison between different studies and laboratories. We propose here a preliminary "best practices" and workflow for characterization of juvenile pyroclasts, for comparative studies of primary fragmentation. If the community follows such a standardized method, it will become possible to accumulate a large volume of consistent data on juvenile pyroclasts from a range of eruption styles, fragmentation mechanisms, and magma compositions. This will ultimately allow deeper insights into the full panoply of magma-to-pyroclast processes that drive particle-producing volcanic eruptions. One or more "fragmentation diagrams" may eventually be developed to allow different types of magmatic and phreatomagmatic explosive eruptions to be distinguished based on their products.

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“…In parallel, in-situ glass and crystal analysis were performed using the same EPMA instrument, with a 15 kV acceleration voltage and a focused spot size (1 µm) for crystals and a spot diameter of 20 µm for the glass. Ash morphology measurements were also carried out using the automatized morpho-grainsizer Malvern Morphologi G3, following the procedure described in Thivet et al (2020a), Thivet et al (2020b). This instrument allows measurement of the Apparent Projected shape of ASH (APASH) on hundreds of ash particles, listing several shape parameters (described in Leibrandt and Le Pennec 2015) for each analyzed particle.…”

Section: Ash Collector and Sizer And Laboratory Ash Characterization: Insights Into Grain Size Distribution And Componentrymentioning

confidence: 99%

Multi-Parametric Field Experiment Links Explosive Activity and Persistent Degassing at Stromboli

et al. 2021

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Visually unattainable magmatic processes in volcanic conduits, such as degassing, are closely linked to eruptive styles at the surface, but their roles are not completely identified and understood. To gain insights, a multi-parametric experiment at Stromboli volcano (Aeolian Islands, Italy) was installed in July 2016 focusing on the normal explosive activity and persistent degassing. During this experiment, gas-dominated (type 0) and particle-loaded (type 1) explosions, already defined by other studies, were clearly identified. A FLIR thermal camera, an Ultra-Violet SO₂ camera and a scanning Differential Optical Absorption Spectroscopy were deployed to record pyroclast and SO2 masses emitted during individual explosions, as well as persistent SO₂ fluxes, respectively. An ASHER instrument was also deployed in order to collect ash fallouts and to measure the grain size distribution of the samples. SO2 measurements confirm that persistent degassing was far greater than that emitted during the explosions. Further, we found that the data could be characterized by two periods. In the first period (25–27 July), activity was mainly characterized by type 0 explosions, characterized by high velocity jets. Pyroclast mass fluxes were relatively low (280 kg/event on average), while persistent SO2 fluxes were high (274 t/d on average). In the second period (29–30 July), activity was mainly characterized by type 1 explosions, characterized by low velocity jets. Pyroclast mass fluxes were almost ten times higher (2,400 kg/event on average), while persistent gas fluxes were significantly lower (82 t/d on average). Ash characterization also indicates that type 0 explosions fragments were characterized by a larger proportion of non-juvenile material compared to type 1 explosions fragments. This week-long field experiment suggests that, at least within short time periods, Stromboli’s type 1 explosions can be associated with low levels of degassing and the mass of particles accompanying such explosive events depends on the volume of a degassed magma cap sitting at the head of the magma column. This could make the classic particle-loaded explosions of Stromboli an aside from the true eruptive state of the volcano. Instead, gas-dominated explosions can be associated with high levels of degassing and are indicative of a highly charged (with gas) system. We thus suggest that relatively deep magmatic processes, such as persistent degassing and slug formation can rapidly influence the superficial behavior of the eruptive conduit, modulating the presence or absence of degassed magma at the explosion/fragmentation level.

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Variability of ash deposits at Piton de la Fournaise (La Reunion Island): insights into fragmentation processes at basaltic shield volcanoes

Cited by 19 publications

References 91 publications

Volcano Crisis Management at Piton de la Fournaise (La Réunion) during the COVID-19 Lockdown

Volcano Crisis Management at Piton de la Fournaise (La Réunion) during the COVID-19 Lockdown

Standardized analysis of juvenile pyroclasts in comparative studies of primary magma fragmentation; 1. Overview and workflow

Multi-Parametric Field Experiment Links Explosive Activity and Persistent Degassing at Stromboli

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