Cookies

We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.


Durham Research Online
You are in:

Explosivity of basaltic lava fountains is controlled by magma rheology, ascent rate and outgassing

La Spina, G. and Arzilli, F. and Llewellin, E.W. and Burton, M.R. and Clarke, A.B. and de' Michieli Vitturi, M. and Polacci, M. and Hartley, M.E. and Di Genova, D. and Mader, H.M. (2021) 'Explosivity of basaltic lava fountains is controlled by magma rheology, ascent rate and outgassing.', Earth and Planetary Science Letters, 553 . p. 116658.

Abstract

The dichotomy between explosive volcanic eruptions, which produce pyroclasts, and effusive eruptions, which produce lava, is defined by the presence or absence of fragmentation during magma ascent. For lava fountains the distinction is unclear, since the liquid phase in the rising magma may remain continuous to the vent, fragment in the fountain, then re-weld on deposition to feed rheomorphic lava flows. Here we use a numerical model to constrain the controls on basaltic eruption style, using Kilauea and Etna as case studies. Based on our results, we propose that lava fountaining is a distinct style, separate from effusive and explosive eruption styles, that is produced when magma ascends rapidly and fragments above the vent, rather than within the conduit. Sensitivity analyses of Kilauea and Etna case studies show that high lava fountains (>50 m high) occur when the Reynolds number of the bubbly magma is greater than ∼0.1, the bulk viscosity is less than 106 Pa s, and the gas is well-coupled to the melt. Explosive eruptions (Plinian and sub-Plinian) are predicted over a wide region of parameter space for higher viscosity basalts, typical of Etna, but over a much narrower region of parameter space for lower viscosity basalts, typical of Kilauea. Numerical results show also that the magma that feeds high lava fountains ascends more rapidly than the magma that feeds explosive eruptions, owing to its lower viscosity. For the Kilauea case study, waning ascent velocity is predicted to produce a progressive evolution from high to weak fountaining, to ultimate effusion; whereas for the Etna case study, small changes in parameter values lead to transitions to and from explosive activity, suggesting that eruption transitions may occur with little warning.

Item Type:Article
Full text:(VoR) Version of Record
Available under License - Creative Commons Attribution 4.0.
Download PDF
(1578Kb)
Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1016/j.epsl.2020.116658
Publisher statement:© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Date accepted:30 October 2020
Date deposited:13 May 2021
Date of first online publication:16 November 2020
Date first made open access:13 May 2021

Save or Share this output

Export:
Export
Look up in GoogleScholar