Pele's tears and spheres: Examples from Kilauea Iki

Porritt, L. A.; Russell, James K.; Quane, Steven L.

doi:10.1016/j.epsl.2012.03.031

Cited by 55 publications

(71 citation statements)

References 16 publications

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“…droplets of lava blown during a volcanic eruption that are deformed by the relative air flow, and solidify in a non spherical shape. 15 The same mechanism has been invoked in the literature as a possible explanation for the non spherical grains obtained from spray-drying processes. 7 In agreement with recent observations, 11 we demonstrate in the following that, in usual spray-drying conditions, that mechanism is not responsible for the non spherical shape of the grains.…”

Section: Hydrodynamic Effectsmentioning

confidence: 76%

Control of particle morphology in the spray drying of colloidal suspensions

et al. 2016

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Powders of nanoparticles are volatile, i.e. easily disperse in air, which makes their handling difficult. Granulation of nanoparticle powders provides a solution to that issue, and it is generally performed by spray drying the nanoparticles that have been suspended in a liquid. Spray drying of a colloidal suspension consists of atomising the suspension into droplets by a fast flowing and hot gas. Once the droplets dried, the resulting dry grains/microparticles can be used in a wide range of applications - food, pharmaceutics, fillers, ceramics, etc. It is well known that the grains resulting from spray-drying may be spherical but may also exhibit other diverse morphologies. Although different influencing parameters have been identified, no clear overview can be found in the literature for the driving mechanisms of grain shaping. In the present work, we review the assumptions made in the literature to explain the different morphologies. We analyse the orders of magnitude of the different effects at stake and show that the grain shape does not result from a hydrodynamic instability but is determined by the drying stage. However, we emphasize that neither the drying time nor the associated Péclet number are critical parameters for the determination of shape morphology. In light of those results, we also review and discuss the single droplet experiments developed to mimic spray drying. Generalising our previous works, we further analyse how the control of morphology can be achieved by tuning the colloidal interactions in the suspension. We detail the model we have developed that relates the colloidal interaction potential to a critical pressure exerted by the solvent as it flows, and we provide a quantitative prediction of the grain shape. Finally, we offer perspectives with regard to spray drying of systems such as molecular solutions, widely performed in e.g. the pharmaceutical industry.

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Section: Hydrodynamic Effectsmentioning

confidence: 76%

Control of particle morphology in the spray drying of colloidal suspensions

et al. 2016

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“…Volcanic ash grains contain structurally bound water and are coated by adsorbed volatiles (e.g., Delmelle et al, 2007) during eruption. Adsorbed volatiles would be vaporized, but expansion of structurally bound volatile compounds during electrical discharge may explain the hollow and/or cracked morphology of volcanic spherules, as observed in Pele's tears (Porritt et al, 2012). Although textures are similar, the magma compositions of Mount Redoubt and Eyjafjallajökull are too viscous (andesite and benmoreite, respectively) compared to that of the Kilauea Iki magma (basalt) to permit the formation of spherical achneliths during primary fragmentation.…”

Section: Discussionmentioning

confidence: 97%

Lightning-induced volcanic spherules

Genareau

Wardman

Wilson

et al. 2015

Geology

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Glass spherules have been documented in many geologic deposits and are formed during high-temperature processes that include cloud-to-ground lightning strikes, volcanic eruptions of low-viscosity magmas, and meteorite impacts. This study reviews the known glass spheruleforming processes and proposes, for the first time, a mechanism induced through the heat generated by volcanic lightning in eruptive columns and plumes (laterally spreading clouds) during explosive eruptions. Ash-fall samples were collected from two eruptions where volcanic lightning was extensively documented: the A.D. 2009 eruption of Mount Redoubt, Alaska (USA), and the 2010 eruption of Eyjafjallajökull, Iceland. These samples reveal individual glass spherules ~50 mm in average diameter that compose <5% of the examined portion of the deposit. Textures include smooth, hollow, or cracked spherules, as well as aggregates, which suggest melting of ash particles as a result of proximity to the electrical discharge channel and subsequent re-solidification of the particles into spherical morphologies. The natural ash-fall samples are compared with pseudo-ash samples collected from high-voltage insulator experiments in order to test our hypothesis that volcanic ash particles can be transformed into glass spherules through the heat generated by electrical discharge. We refer to this new morphological classification of ash grains as lightning-induced volcanic spherules and hypothesize that this texture not only provides direct physical evidence of lightning occurrence during explosive eruptions, but will also increase settling velocities and reduce aggregation of these particles, affecting ash transport dynamics.

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“…Because the eruption produced a large amount of ash compared to the other recent eruptive fissures at PdF (DynVolc ), we mostly focused on the ash particles to perform the glass composition measurements, petrology analysis, and the microtexture characterization. Moreover, we suggest that the ash can conserve the more pristine signature of the fragmentation processes because of the relatively fast natural quenching in air (D'Oriano et al, ; Di Muro et al, ; Potuzak et al, ; Porritt et al, ; Pompilio et al, ; Xu & Zhang, ) compared to the large lapilli and the inner parts of the bomb‐sized tephra. The golden/fluidal glass compositions (Figure ) range between 6.14 and 6.94 wt% in MgO, between 0.79 and 0.83 in CaO/Al 2 O 3 , and between 0.64 and 0.87 wt% in K 2 O.…”

Section: Resultsmentioning

confidence: 81%

Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France)

Thivet

Gurioli

Muro

et al. 2020

Geochem Geophys Geosyst

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In September 2016, Piton de la Fournaise volcano, well known for its effusive and Hawaiian fountaining activity, produced, at the end of the eruption, an unusual phase of pulsating ash and bomb emission. Integration of geophysical data, with textural and petrological analysis of the samples, allowed us to constrain the main factors that controlled this sudden shift in activity, potentially dangerous for the tourist population that usually approach these “gentle” eruptive sites. Volcanic tremor, lava discharge rates, fountain heights, and SO2 emission changed rapidly during the eruption. Grain size and componentry of the tephra beds evolved from unimodal all along the sequence to bimodal on the last day of the activity, reflecting the contribution of both Hawaiian fountaining at the main vent (Vent A) and transient explosive activity at the second vent (Vent B). Hawaiian fountaining produced highly vesicular and almost microlite‐free tephra (golden pumice and fluidal scoria) while transient explosive activity emitted denser and crystal‐rich tephra (sideromelane and tachylite scoria) sometimes mingled with vesicular fragments. Permeability measurements on lapilli and bomb‐sized samples reveal that golden pumice and fluidal scoria were more gas‐permeable than the sideromelane and tachylite ones, while textural and chemical analyses of the ash support the hypothesis that these sideromelane and tachylite components were inherited from the subsurface crystallization of the initial golden pumice and fluidal scoria components. We thus suggest that Vent B accumulated a plug of degassed, cooled, and low‐permeable magma, which modulated overpressure pulses under the late input of ascending magma.

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Pele's tears and spheres: Examples from Kilauea Iki

Cited by 55 publications

References 16 publications

Control of particle morphology in the spray drying of colloidal suspensions

Control of particle morphology in the spray drying of colloidal suspensions

Lightning-induced volcanic spherules

Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France)

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