Scientific article
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In-situ evidence of volcanic ash aggregation during fallout from combined ground- and UAS-based observations

Published inScientific reports, vol. 16, 15083
Publication date2026-03-26
First online date2026-03-26
Abstract

This study investigates the sedimentation of volcanic particles from low-altitude (< 2 km a.s.l.), near-daily ash plumes and clouds at Sakurajima volcano (Japan). Plume dynamics were monitored using imagery (visible wavelength) and geophysical (ash discharge rates) data. Ash fallout was characterized by using ground-based (disdrometer, particle electrical charge sensor, and sampling) and drone-mounted (optical particle counter, atmospheric sensor, and sampling) instruments. A comparison of particle size distributions and aggregate proportions between samples collected by drone 500 m above the take-off sites and those collected on the ground shows that aggregation develops rapidly during sedimentation. This process involves collisions between coarse ash (up to 1 mm) and fine ash particles (< 63 µm). Particle binding is promoted by electrostatic attraction (forming particle clusters) or high atmospheric humidity (forming accretionary pellets). These results provide innovative in-situ evidence of ash aggregation, offering new insights into its dynamics in natural settings, crucial for improving volcanic ash dispersion forecasting.

Citation (ISO format)
THIVET, Simon et al. In-situ evidence of volcanic ash aggregation during fallout from combined ground- and UAS-based observations. In: Scientific reports, 2026, vol. 16, p. 15083. doi: 10.1038/s41598-026-45460-x
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Additional URL for this publicationhttps://www.nature.com/articles/s41598-026-45460-x
Journal ISSN2045-2322
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