Syn-eruptive hydration of volcanic ash records pyroclast-water interaction in explosive eruptions

Geophysical Research Letters
By: , and 

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Abstract

Magma-water interaction can dramatically influence the explosivity of volcanic eruptions. However, syn- and post-eruptive diffusion of external (non-magmatic) water into volcanic glass remains poorly constrained and may bias interpretation of water in juvenile products. Hydrogen isotopes in ash from the 2009 eruption of Redoubt Volcano, Alaska, record syn-eruptive hydration by vaporized glacial meltwater. Both ash aggregation and hydration occurred in the wettest regions of the plume, which resulted in the removal and deposition of the most hydrated ash in proximal areas <50 km from the vent. Diffusion models show that the high temperatures of pyroclast-water interactions (>400°C) are more important than the cooling rate in facilitating hydration. These observations suggest that syn-eruptive glass hydration occurred where meltwater was entrained at high temperature, in the plume margins near the vent. Ash in the drier plume interior remained insulated from entrained meltwater until it cooled sufficiently to avoid significant hydration.

Publication type Article
Publication Subtype Journal Article
Title Syn-eruptive hydration of volcanic ash records pyroclast-water interaction in explosive eruptions
Series title Geophysical Research Letters
DOI 10.1029/2021GL094141
Volume 48
Issue 23
Year Published 2021
Language English
Publisher American Geophysical Union
Contributing office(s) Volcano Science Center
Description e2021GL094141, 8 p.
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