Influence of grain size and shape on volcanic ash electrical conductivity

Journal of Volcanology and Geothermal Research
By: , and 

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Abstract

Few studies have examined the electrical properties of volcanic ash or considered the effects of physical characteristics, such as grain size and shape on its electrification. This study measures the resistivity of eight volcanic ash samples, three milled-samples and five natural ashfall samples from Alaska, U.S.A., using a current amplifier and examines the influence of particle size and particle shape on calculated grain conductivity. Grain conductivities are calculated by applying spherical, oblate, and prolate ellipsoidal shape parameters within a general effective media equation. Volcanic ash is an electrically insulating material with average resistivity values ranging from 1.732E7 to 1.606E12 Ωm. Results show that grain size has a limited impact on resistivity. Calculated grain conductivities remained within the same order of magnitude between the three different shape calculations ranging between 1.367E7 and 2.196E12 S/m using the spherical shape parameter. Electrical measurements of heterogeneous powders are complex and challenging. This study aims to expand the community's dataset and understanding of the electrical properties of volcanic ash and the impact of different physical characteristics. This has implication for understanding ash hazards to electrical infrastructure and volcanic lightning.

Publication type Article
Publication Subtype Journal Article
Title Influence of grain size and shape on volcanic ash electrical conductivity
Series title Journal of Volcanology and Geothermal Research
DOI 10.1016/j.jvolgeores.2020.106788
Volume 393
Year Published 2020
Language English
Publisher Elsevier
Contributing office(s) Volcano Science Center
Description 106788, 9 p.
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