Petrologic monitoring at Volcán de Fuego, Guatemala

Liu, Emma J. and Cashman, Katharine V. and Miller, Ellen and Moore, Hannah and Edmonds, Marie and Kunz, Barbara E. and Jenner, Frances and Chigna, Gustavo (2020) Petrologic monitoring at Volcán de Fuego, Guatemala. Journal of Volcanology and Geothermal Research, 405. p. 107044. ISSN 0377-0273 DOI

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Paroxysmal activity represents an end-member in the common range of activity at mafic arc volcanoes, characterised by rapid transitions across the effusive-explosive interface and thus posing significant challenges to hazard assessment. Conceptual models to explain changes in the frequency and magnitude of these paroxysmal events are based either on magma recharge or an increase in gas flux, largely framed in the context of two-phase flow. Gas- and magma-driven models are both viable mechanisms to explain the varying styles of paroxysmal behaviour observed in mafic systems; however, each has different implications for future activity. We present time series petrologic data for ash and lava samples collected at Volcán de Fuego, Guatemala, during paroxysmal eruptions between 2011 and 2018. We show that a step-change in glass composition occurred between 2015 and 2016, reflecting an increase in magma temperature and a reduction in pre-eruptive crystallisation, concurrent with an escalation in the frequency of paroxysmal activity. There was no change in the bulk or phase compositions during this period. To explain these observations, we propose that the increase in frequency of paroxysmal eruptions is modulated by the supply of exsolved volatiles from lower crustal degassing magmas, without invoking repeated transfer of new, primitive magma to a shallow reservoir. Protracted lava effusion, accompanied by more vigorous and more frequent Strombolian explosions and gas ‘chugging’, prior to the transition to sustained fountaining suggests that gas retention in crystal-rich magma may modulate the height of the magma column as gas supply increases.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
06 - Part-III Projects
Journal or Publication Title: Journal of Volcanology and Geothermal Research
Volume: 405
Page Range: p. 107044
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 06 Nov 2020 01:53
Last Modified: 06 Nov 2020 01:53

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