气候变化领域集成服务门户(CCPortal): Influence of shock propagation on lightning evidence in volcanic ashfall deposits

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DOI	10.1016/j.epsl.2020.116124
	Influence of shock propagation on lightning evidence in volcanic ashfall deposits
	Genareau K.; Gharghabi P.; Klüss J.
发表日期	2020
ISSN	0012821X
卷号	535
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
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202605
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
推荐引用方式 GB/T 7714	Genareau K.,Gharghabi P.,Klüss J.. Influence of shock propagation on lightning evidence in volcanic ashfall deposits[J],2020,535.
APA	Genareau K.,Gharghabi P.,&Klüss J..(2020).Influence of shock propagation on lightning evidence in volcanic ashfall deposits.Earth and Planetary Science Letters,535.
MLA	Genareau K.,et al."Influence of shock propagation on lightning evidence in volcanic ashfall deposits".Earth and Planetary Science Letters 535(2020).