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Pre-eruptive vapour and its role in controlling eruption style and longevity at Soufriere Hills Volcano

Edmonds, M.; Humphreys, M.C.S.; Hauri, E.; Herd, R.; Wadge, G.; Rawson, H.; Ledden, R.; Plail, M.; Barclay, J.; Aiuppa, A.; Christopher, T.; Giudice, G.; Guida, R.

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Authors

M. Edmonds

E. Hauri

R. Herd

G. Wadge

H. Rawson

R. Ledden

M. Plail

J. Barclay

A. Aiuppa

T. Christopher

G. Giudice

R. Guida



Contributors

G. Wadge
Editor

R.E.A. Robertson
Editor

B. Voight
Editor

Abstract

We use volatiles in melt inclusions and nominally anhydrous phenocrysts, with volcanic gas flux and composition, and textural analysis of mafic inclusions to estimate the mass of exsolved vapour prior to eruption at Soufrière Hills Volcano (SHV). Pre-eruptive andesite coexists with exsolved vapour comprising 1.6–2.4 wt% of the bulk magma. The water content of orthopyroxenes indicates a zone of magma storage at pressures of approximately 200–300 MPa, whereas melt inclusions have equilibrated at shallower pressures. Inclusions containing >3 wt% H2O are enriched in CO2, suggesting flushing with CO2-rich gases. Intruding mafic magma contains >8 wt% H2O at 200–300 MPa. Rapid quenching is accompanied by crystallization and vesiculation. Upon entrainment into the andesite, mafic inclusions may undergo disaggregation, where expansion of volatiles in the interior overcomes the strength of the crystal frameworks, thereby recharging the vapour content of the andesite. Exsolved vapour may amount to 4.3–8.2 vol% at 300 MPa, with implications for eruption longevity and volume; we estimate the magma reservoir volume to be 60–200 km3. Exsolved vapour may account for the small volume change at depth during eruptions from geodetic models, and has implications for magma flow: exsolution is likely to be in equilibrium during rapid magma ascent, with little nucleation of new bubbles.

Citation

Edmonds, M., Humphreys, M., Hauri, E., Herd, R., Wadge, G., Rawson, H., …Guida, R. (2014). Pre-eruptive vapour and its role in controlling eruption style and longevity at Soufriere Hills Volcano. In G. Wadge, R. Robertson, & B. Voight (Eds.), The eruption of Soufrière Hills Volcano, Montserrat from 2000 to 2010 (291-315). The Geological Society. https://doi.org/10.1144/m39.16

Online Publication Date Jun 2, 2014
Publication Date Sep 1, 2014
Deposit Date Feb 4, 2014
Publicly Available Date Sep 17, 2014
Publisher The Geological Society
Pages 291-315
Series Title Geological Society of London, Memoirs
Series Number 39
Book Title The eruption of Soufrière Hills Volcano, Montserrat from 2000 to 2010.
Chapter Number 16
DOI https://doi.org/10.1144/m39.16

Files

Accepted Book Chapter (4.8 Mb)
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Copyright Statement
© Geological Society of London 2014





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