Timescales of Water Accumulation in Magmas and Implications for Short Warning Times of Explosive Eruptions

M. Petrelli , Kamal El Omari (1) , L. Spina , Yves Le Guer (1) , G. La Spina , D. Perugini (2)

1 SIAME - Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au génie Electrique
2 Department of Earth Sciences [Perugia]

Water plays a key role in magma genesis, differentiation, ascent and, finally, eruption. Despite the recognized crucial function of water, there are still several issues that continue to blur our view about its role in magmatic systems. What are the timescales of H2O accumulation in crystallizing magmas? What are the ascent rates of water-rich residual melts leading to explosive eruptions? Here, we track the timescale of water accumulation in a residual melt resulting from crystallization of a hydrous CO2-bearing magmatic mass stored at mid-to deep-crustal levels in a subduction-related geodynamic setting. Our results indicate that, after a repose period ranging from few to several thousand years, water-rich melts with water concentrations larger than 6-9 wt.% can migrate towards the Earth surface in very short timescales, on the order of days or even hours, possibly triggering explosive eruptions with short warning times and devoid of long-term geophysical precursors. \textcopyright 2018 The Author(s).

Keywords: Volcanology; Petrology; Natural hazards

Domains: Physics [physics]

M. Petrelli, Kamal El Omari, L. Spina, Yves Le Guer, G. La Spina, et al.. Timescales of Water Accumulation in Magmas and Implications for Short Warning Times of Explosive Eruptions. Nature Communications, 2018, 9 (1), pp.art. 770. ⟨10.1038/s41467-018-02987-6⟩. ⟨hal-02146091⟩