The transcrustal magma reservoir beneath Soufrière Hills Volcano, Montserrat: insights from 3-D geodetic inversions

Joachim H Gottsmann*, James Hickey, Molly Flynn

*Corresponding author for this work

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Abstract

We invert intra-eruptive ground displacements recorded between 2003-2005 on Montserrat to shed light on the magmatic plumbing system of Soufrière Hills Volcano. Incorporating 3-dimensional crustal mechanical and topographic data in a finite-element model we show that the recorded displacements are best explained by a southeastward dipping (plunge angle of 9.3˚) vertically extended tri-axial ellipsoidal pressure source with semi-axis lengths of 1.9 and 2.0 km horizontally, and 5.0 km vertically. The source is centred at 9.35 km depth below main sea level and embedded in independently imaged anomalously weak crustal rocks. The source orientation appears to be controlled by the local stress field at the intersection of two major WNW-ESE and NW-SE striking tectonic lineaments. We derive an average volumetric strain rate of 8.4 x10-12 s-1 by transcrustal pressurisation which may have contributed to flank instability and mass wasting events in the southern and eastern sectors of the island.
Original languageEnglish
Article numbere2020GL089239
Number of pages10
JournalGeophysical Research Letters
Volume47
Issue number20
DOIs
Publication statusPublished - 17 Oct 2020

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