Analysis of magma flux and eruption intensity during the 2021 explosive activity at the Soufrière of St Vincent, West Indies

Sparks, R. J. Steve, Aspinall, Willy P., Barclay, Jenni ORCID: https://orcid.org/0000-0002-6122-197X, Renfrew, Ian ORCID: https://orcid.org/0000-0001-9379-8215, Contreras-Arratia, Rodrigo and Stewart, Robert (2024) Analysis of magma flux and eruption intensity during the 2021 explosive activity at the Soufrière of St Vincent, West Indies. In: Geological Society Special Publication. Geological Society Special Publications, 539 (1). Geological Society of London.

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Abstract

Seismic RSAM signals and eruption cloud height measurements were used to estimate peak intensities of 40 explosive events during the 8-22 April 2021 activity of the Soufrière volcano. We estimated magma supply rates and erupted volumes in each explosion, characterized uncertainty by stochastic modelling and identified four eruptive stages. Stage 1 included an intense period of 9.5 hours with 11 explosive events with peak eruption intensity between 2000 and 4000 m3/s and magma supply rate reaching 828 m3/s. 12 high intensity explosions (∼4000 m3/s) occurred in Stage 2 with average magma supply rate of 251 m3/s. Stage 3 involved declining intensity, magma supply rate and lengthening repose periods between explosions. Stage 4 involved 3 much weaker explosions. The total erupted volume of magma is estimated at 38.5 × 106 m3 (90% credible interval: [22.0 .. 61.9] × 106 m3) consistent with independent estimates from analysis of tephra deposits and volcano subsidence sourced at ∼6 km depth. The 150-fold increase in magma supply rate, from the preceding effusive phase to Stage 1 of the explosive phase, is attributed to replacement of very high viscosity degassed magma occupying the shallow conduit system with new lower viscosity volatile-rich magma from the magma chamber. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6558003

Item Type:	Book Section
Additional Information:	Issue: The 2020-21 Eruption of La Soufrière Volcano, St Vincent
Faculty \ School:	Faculty of Science > School of Environmental Sciences University of East Anglia > Theme - ClimateUEA
Depositing User:	LivePure Connector
Date Deposited:	03 May 2023 13:30
Last Modified:	03 May 2023 13:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/91984
DOI:	10.1144/SP539-2022-286

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