Volatile emissions and magma storage conditions for the 2021 explosive eruption at La Soufrière volcano, St Vincent from melt inclusions

ORCID

Abstract

The VEI 4 eruption of La Soufrière volcano underwent a dramatic transition in style from initial lava dome effusion in December 2020 to hazardous explosive activity in April 2021. Understanding the magmatic processes underpinning such transitions is critical. We provide the first comprehensive dataset of the compositions and volatile contents of melt inclusions from the 2021 explosive activity, including the first measurements of pre-eruptive total CO2 at La Soufrière and estimates of magmatic temperature. We use the petrological method to quantify volatile fluxes to the atmosphere of 5.40±0.60 Mt H2O, 0.37±0.04 Mt CO2, 0.13±0.01 Mt SO2, and 0.33±0.04 Mt HCl. Modelling of volatile saturation pressures indicates final magma storage depths of 2.4-8.9 km (mean 6.4 km) throughout four phases of explosive activity after migration of magma in the lower storage region within the transcrustal mush system. Inferred depths are consistent with recorded seismicity and deformation before and during the explosions.

Publication Date

2026-02-11

Publication Title

Volcanica

Volume

9

Issue

1

Acceptance Date

2026-01-23

Deposit Date

2026-01-27

Funding

This study was supported by a Government of Montserrat PhD scholarship awarded to TAH. We thank Cees-Jan de Hoog for assistance with ionprobe analysis, Jean Luc Deval for assistance with microprobe analysis and Claire Fonquernie for whole rock analysis. Raman and whole rock analyses were funded by the Volcanology team at Laboratoire Magmas et Volcans. We are grateful to David Neave and Margaret Hartley for discussions on melt inclusion reconstruction.

Keywords

Lesser Antilles, Magma degassing, Melt inclusion, Vapour bubble, Volatile budget, Volatile emissions

First Page

231

Last Page

258

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