Influence of shock propagation on lightning evidence in volcanic ashfall deposits

Genareau, Kimberly; Gharghabi, Pedram; Klüss, Joni

doi:10.1016/j.epsl.2020.116124

Cited by 8 publications

(9 citation statements)

References 40 publications

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“…3c,g). Results of the high current impulse experiments by Generau et al 21 also supports our nding in that the initial high current impulse alone is not su cient to produce enough melting to generate a fulgurite body. The addition of a prolonged continuing current phase, instead, allows the necessary energy (heat) transfer required to sustain the melting process of the pristine material, which has also associated with lightning-ignited res 33,34,35 .…”

Section: Discussionsupporting

confidence: 88%

“…20-60 kV) was, for example, insu cient to create fulgurites closely resembling natural ones 15,16 . Subsequent experiment setups were missing inductivity 17 , and/or they produced solely a rst-return stroke component (the component of the lightning discharge vital for breaking down the dielectric eld strength of the original material) 18,21 . The pulse they generated using the sinusoidal waveform aids the dielectric breakdown of the sample, ultimately generating melting, but it is not su cient to reproduce the typical morphology of fulgurites 19 .…”

Section: Introductionmentioning

confidence: 99%

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Experimental generation of fulgurite under realistic lightning discharge conditions

Çalışkanoğlu

Camara

Cimarelli

et al. 2023

Preprint

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Fulgurites have been documented in geological deposits from throughout Earth's history. They have also been assigned a potential role in prebiotic chemistry as a source of reactants. Fulgurites are generated in nature by cloud-to-ground lightning strikes. The unpredictability in space and time of the occurrence of lightning events has limited the investigation of both the mechanisms by, and the conditions under, which fulgurites form. A laboratory-based approach can ameliorate this. Here, we describe experimentally generated fulgurites generated from Laacher See volcanic ash. We employ a DC source with a trigger-pulse setup in a high voltage laboratory, whose capabilities enable experimental conditions that correspond closely to the electrical characteristics of natural lightning strikes. The experimentally generated fulgurites closely resemble naturally-occurring fulgurites in both state and texture. These experimental investigations yield a high reproducibility of the characteristic of fulgurites generated under well-constrained conditions, enabling some inferences to be made regarding the processes involved in the generation of fulgurites in nature. This work provides a basis for a systematic characterization of experimental fulgurites and the characteristic of lightning discharges.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Experimental generation of fulgurite under realistic lightning discharge conditions

Çalışkanoğlu

Camara

Cimarelli

et al. 2023

Preprint

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“…Particles may also vesiculate by exsolution of residual volatiles in the glass phase, analogous to natural lightning-induced pumiceous particles (Genareau et al 2019a ). Additionally, the magnetic properties of the particles change, showing increased magnetization (Genareau et al 2019b ), similar to locations struck by cloud-to-ground lightning (Cox 1961 ; Sakai et al 1998 ; Verrier and Rochette 2002 ).…”

Section: Experimental Generation Of Lightning and Lightning Simulatio...mentioning

confidence: 84%

Volcanic electrification: recent advances and future perspectives

et al. 2022

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The electrification of volcanic plumes has been described intermittently since at least the time of Pliny the Younger and the 79 AD eruption of Vesuvius. Although sometimes disregarded in the past as secondary effects, recent work suggests that the electrical properties of volcanic plumes reveal intrinsic and otherwise inaccessible parameters of explosive eruptions. An increasing number of volcanic lightning studies across the last decade have shown that electrification is ubiquitous in volcanic plumes. Technological advances in engineering and numerical modelling, paired with close observation of recent eruptions and dedicated laboratory studies (shock-tube and current impulse experiments), show that charge generation and electrical activity are related to the physical, chemical, and dynamic processes underpinning the eruption itself. Refining our understanding of volcanic plume electrification will continue advancing the fundamental understanding of eruptive processes to improve volcano monitoring. Realizing this goal, however, requires an interdisciplinary approach at the intersection of volcanology, atmospheric science, atmospheric electricity, and engineering. Our paper summarizes the rapid and steady progress achieved in recent volcanic lightning research and provides a vision for future developments in this growing field.

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“…Analogous to thunderstorm lightning (Aizawa et al., 2016), temperatures may reach 30000°C at the channel axis (Rakov & Uman, 2003; Uman, 1964), irrevocably altering volcanic ash (<2 mm) particles by instantaneously (<milliseconds) melting and volatilizing grains proximal to the axis (Genareau, Hong, et al., 2019; Genareau, Wallace, et al., 2019; Genareau et al., 2017; Wadsworth et al., 2017). Before the discharge dissipates and molten particles quench into glass, various shapes can form through a combination of mechanisms involving melting and re‐solidification of individual (<150 μm) grains (Wadsworth et al., 2017), fusion of multiple molten particles into single or aggregated particles (Genareau et al., 2017), detachment of expanding bubbles from vesiculated grains (Genareau, Wallace, et al., 2019), and flattening or elongation of molten particles due to shock front propagation (Genareau et al., 2020). Lightning‐induced textures include hollow or solid lightning‐induced volcanic spherules (LIVS), spherule aggregates, pumiceous particles, hair‐like particles, and plate‐like particles.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Lightning‐Induced Glass Produced From Five Mineral Phases

Woods,

Feinberg,

Genareau

et al. 2023

JGR Solid Earth

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The physical properties of minerals are modified by the high temperatures of volcanic lightning during explosive eruptions. Alteration involves rapid heating and volatilization, melting, and fusion of ash grains within the discharge channel, followed by rapid quenching into new glassy textures. High current impulse experiments reveal that lightning alters not only the morphology and mineralogy of volcanic ash but also its magnetic properties. We investigate lightning‐induced magnetic changes in five igneous minerals (< 32 µm powders of albite, labradorite, augite, hornblende, and magnetite) by comparing hysteresis parameters before and after impulse experiments conducted at peak currents of 25 and 40 kA. Both the paramagnetic and ferrimagnetic behaviors of the samples were altered, which we interpret as a superposition of two processes. (1) Rapid melting allows iron contained within inclusions of Fe‐oxides and Fe‐bearing silicates to diffuse into the newly formed melt, thereby increasing the paramagnetism of the resulting glass. (2) Nucleation and growth of magnetite from the newly formed melt increases the ferrimagnetic behavior of the post‐experimental samples. Nominally non‐Fe‐bearing silicates like albite and labradorite have significantly increased paramagnetism and ferrimagnetism. Fe‐bearing silicates like augite and hornblende contain higher concentrations of ferrimagnetic inclusions, from which Fe diffuses into the newly formed melt, thereby increasing paramagnetism while decreasing ferrimagnetism. Experiments conducted on magnetite produced new magnetite crystals with dendritic habits. Although specific to volcanic ash, these results provide important insights into the magnetism of other materials affected by lightning on Earth, the Moon, and throughout the solar system.

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Influence of shock propagation on lightning evidence in volcanic ashfall deposits

Cited by 8 publications

References 40 publications

Experimental generation of fulgurite under realistic lightning discharge conditions

Experimental generation of fulgurite under realistic lightning discharge conditions

Volcanic electrification: recent advances and future perspectives

Magnetic Properties of Lightning‐Induced Glass Produced From Five Mineral Phases

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