DOI: 10.1016/j.epsl.2020.116124
论文题名: Influence of shock propagation on lightning evidence in volcanic ashfall deposits
作者: Genareau K. ; Gharghabi P. ; Klüss J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 535 语种: 英语
中文关键词: ashfall
; current impulse
; lightning-induced textures
; shock front
; volcanic lightning
英文关键词: Aggregates
; Clouds
; Deposits
; Expansion
; Explosives
; Lightning
; Shock waves
; Silica
; Textures
; ashfall
; Current impulse
; Lightning induced
; Shock fronts
; Volcanic lightning
; Volcanoes
; ash flow
; atmospheric chemistry
; cloud to ground lightning
; experimental study
; high temperature
; lightning
; pumice
; volcanic ash
; volcanic eruption
英文摘要: Lightning-induced textures in volcanic ashfall deposits can take several forms, including lightning-induced volcanic spherules (LIVS), spherule aggregates, and pumiceous particles. Here, two newly identified textures are described in the products of current impulse experiments conducted on ash samples spanning a range of bulk compositions from basic (49 wt% SiO2) to intermediate (53–58 wt% SiO2) to acidic (72–76 wt% SiO2), at peak currents of 7 kA, 25 kA, and 100 kA. Due to the location of subjected samples on a solid, flat surface in the experimental apparatus, both hair-like particles (1–10 μm in diameter) and plate-like particles (>100 μm in diameter) are produced. These textures result from not only the high temperatures generated by the discharge (>1500 °C), but also by the expansion of a shock front with a radius twice the size of the discharge channel. The pressure behind this shock front ranges from 0.41 MPa for the 7 kA impulse currents to 0.77 MPa for the 100 kA impulse currents and the velocity of the shock ranges from 617 m/s to 846 m/s. The combined high temperatures and shock wave expansion simultaneously melts the volcanic ash particles, fuses them together, and stretches them out, which alters the very small (<32 μm) angular grains into larger hair-like and plate-like shapes. Although LIVS, spherule aggregates, and pumiceous particles have been documented in ashfall samples from explosive volcanic eruptions, these newly identified hair-like and plate-like textures have not. The existence of hair-like and plate-like particles in volcanic ashfall samples expands the variability of lightning evidence and may indicate the occurrence of cloud-to-ground lightning discharges during explosive eruptions. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164983
Appears in Collections: 气候变化与战略
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作者单位: Department of Geological Sciences, The University of Alabama, 201 7th Ave., Tuscaloosa, AL 35487, United States; Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762, United States
Recommended Citation:
Genareau K.,Gharghabi P.,Klüss J.. Influence of shock propagation on lightning evidence in volcanic ashfall deposits[J]. Earth and Planetary Science Letters,2020-01-01,535