ORCID

Abstract

This paper forensically reconstructs the timings, impacts and processes that drove the sequence of explosive eruptions of La Soufrière, St Vincent in April 2021 using a combination of field-based stratigraphy and textural dissection of the deposit character together with contemporary visual observations.Explosive activity on 9 April and early on 10 April involved destruction of almost all of the 2020/2021 lava dome, c. 60% of the 1979 dome and formation of a 600 m diameter crater by 2pm UTC on 10 April. Following the initial explosion, plumes rose to altitudes of c. 15 km and pyroclastic density currents (PDCs), formed by column collapse, first occurred on 10 April, only after >24 h of explosive activity. Dense PDCs reached the sea only in the Larikai and Roseau valleys, and dilute PDCs were restricted to within 2.5 km of the Summit Crater rim.The tephra fallout deposits are stratified, composed of numerous layers of both lapilli-rich and ash-rich layers, which we have grouped into at least 7 units, based on their common characteristics (Units 1 to 7).Volume estimates, using a range of techniques to constrain uncertainties, indicate that the bulk volume of tephra (fallout and PDC) is 1.19 × 108 m3 ± 20% making this a VEI 4 eruption.

Publication Date

2024-01-05

Publication Title

Geological Society Special Publications

Volume

539

ISSN

2041-4927

Acceptance Date

2023-01-03

Deposit Date

2023-07-02

Embargo Period

2023-03-24

Funding

Fieldwork and rock analysis was funded by NERC Urgency NE/W000725/1 to JB and PDC, and also by Royal Society APEX Award (grant: APX/ R1/180094) to JB. RC acknowledges the support from the U.S. National Science Foundation (NSF) grant #1841928.

First Page

81

Last Page

106

Download

Share

COinS