Lightning-Induced Volcanic Spherules
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 spherule–forming processes and propose...
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Digital Commons @ University of South Florida
2015
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Online Access: | https://digitalcommons.usf.edu/geo_facpub/1438 https://doi.org/10.1130/G36255.1 |
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ftusouthflorida:oai:digitalcommons.usf.edu:geo_facpub-2412 2023-07-30T04:03:23+02:00 Lightning-Induced Volcanic Spherules Genareau, Kimberly Wardman, John B. Wilson, Thomas M. McNutt, Stephen R. Izbekov, Pavel 2015-04-01T07:00:00Z https://digitalcommons.usf.edu/geo_facpub/1438 https://doi.org/10.1130/G36255.1 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/geo_facpub/1438 doi:10.1130/G36255.1 https://doi.org/10.1130/G36255.1 School of Geosciences Faculty and Staff Publications Alaska igneous rocks glasses Eyjafjallajokull volcanic glass United States Europe pyroclastics Iceland Redoubt volcanic rocks Western Europe Earth Sciences article 2015 ftusouthflorida https://doi.org/10.1130/G36255.1 2023-07-13T21:56:30Z 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 spherule–forming 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 μm 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. Article in Journal/Newspaper Eyjafjallajökull Iceland Alaska University of South Florida St. Petersburg: Digital USFSP Eyjafjallajokull ENVELOPE(-19.633,-19.633,63.631,63.631) Geology 43 4 319 322 |
institution |
Open Polar |
collection |
University of South Florida St. Petersburg: Digital USFSP |
op_collection_id |
ftusouthflorida |
language |
unknown |
topic |
Alaska igneous rocks glasses Eyjafjallajokull volcanic glass United States Europe pyroclastics Iceland Redoubt volcanic rocks Western Europe Earth Sciences |
spellingShingle |
Alaska igneous rocks glasses Eyjafjallajokull volcanic glass United States Europe pyroclastics Iceland Redoubt volcanic rocks Western Europe Earth Sciences Genareau, Kimberly Wardman, John B. Wilson, Thomas M. McNutt, Stephen R. Izbekov, Pavel Lightning-Induced Volcanic Spherules |
topic_facet |
Alaska igneous rocks glasses Eyjafjallajokull volcanic glass United States Europe pyroclastics Iceland Redoubt volcanic rocks Western Europe Earth Sciences |
description |
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 spherule–forming 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 μm 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. |
format |
Article in Journal/Newspaper |
author |
Genareau, Kimberly Wardman, John B. Wilson, Thomas M. McNutt, Stephen R. Izbekov, Pavel |
author_facet |
Genareau, Kimberly Wardman, John B. Wilson, Thomas M. McNutt, Stephen R. Izbekov, Pavel |
author_sort |
Genareau, Kimberly |
title |
Lightning-Induced Volcanic Spherules |
title_short |
Lightning-Induced Volcanic Spherules |
title_full |
Lightning-Induced Volcanic Spherules |
title_fullStr |
Lightning-Induced Volcanic Spherules |
title_full_unstemmed |
Lightning-Induced Volcanic Spherules |
title_sort |
lightning-induced volcanic spherules |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2015 |
url |
https://digitalcommons.usf.edu/geo_facpub/1438 https://doi.org/10.1130/G36255.1 |
long_lat |
ENVELOPE(-19.633,-19.633,63.631,63.631) |
geographic |
Eyjafjallajokull |
geographic_facet |
Eyjafjallajokull |
genre |
Eyjafjallajökull Iceland Alaska |
genre_facet |
Eyjafjallajökull Iceland Alaska |
op_source |
School of Geosciences Faculty and Staff Publications |
op_relation |
https://digitalcommons.usf.edu/geo_facpub/1438 doi:10.1130/G36255.1 https://doi.org/10.1130/G36255.1 |
op_doi |
https://doi.org/10.1130/G36255.1 |
container_title |
Geology |
container_volume |
43 |
container_issue |
4 |
container_start_page |
319 |
op_container_end_page |
322 |
_version_ |
1772814379038801920 |