Volcanic domes through time: deconstructing morphology and stability hazards as a function of viscosity and alteration

 

PhD Candidate: Kendra Ní Nualláin

Supervisor:Dr. Claire E. Harnett

Funded by:Irish Research Council, European Research Council Synergy Grant, ROTTnROCK

Abstract:

Volcanic lava domes form when lava piles up around a volcanic vent because it is too viscous to flow away [1]. Volcanic domes are inherently unstable structures as they grow incrementally, with varied extrusion rates and material properties. After emplacement, dome stability is further affected by circulation of hot and acidic fluids in the volcano. The interaction of hydrothermal fluids with volcanic rocks alter the rock’s physical and chemical properties, affecting dome morphology and stability [2], [3]. Volcanic dome collapse generates turbulent avalanches that can devastate surrounding communities and affect a volcano’s eruptive dynamics. 

Volcanic domes comprise a fluid inner core and a brittle but fractured outer shell, however the relative proportions remain poorly understood. Understanding internal structure is key to informing hazard, as exposing the hot core to atmospheric pressure (e.g., through volcanic landsliding) can generate explosions. Hydrothermal alteration concentrates at areas of high fluid flow, including the fractured outer shell. Therefore, a combined understanding of the dome structure, alteration effects, and implications for stability is key to forecasting volcanic hazard [4]. Existing computational simulations of volcanic dome growth lack the numerical complexity to consider magma viscosity and post-emplacement processes. Existing models are 2D, which limits their application for hazard assessment. 

The main aims of this project are therefore to determine (1) the influence of viscosity on internal dome structure; (2) the temporal evolution of the dome interior as domes grow and cool; (3) dome stability as a function of viscosity-dependent morphological variations; and (4) the effects of hydrothermal alteration throughout the complex life cycle of the dome. We design an innovative 3D modelling methodology that allows simulation of the full dome life cycle, including extrusion, cooling and solidification, and post-emplacement alteration processes. This project will lead to cutting-edge technical advances and provide new insights into 3D volcano stability hazards.

 References:

[1] Calder, E. S., Lavallée, Y., Kendrick, J. E., & Bernstein, M. (2015). Lava eruptions. In The encyclopedia of volcanoes (pp. 343-362). Academic Press.

[2] Rosas-Carbajal, M., Komorowski, J. C., Nicollin, F., & Gibert, D. (2016). Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics. Scientific reports, 6(1), 29899.

[3] Heap, M. J., Harnett, C. E., Wadsworth, F. B., Gilg, H. A., Carbillet, L., Rosas-Carbajal, M., ... & Moretti, R. (2022). The tensile strength of hydrothermally altered volcanic rocks. Journal of Volcanology and Geothermal Research, 428, 107576.

[4] Reid, M. E., Sisson, T. W., & Brien, D. L. (2001). Volcano collapse promoted by hydrothermal alteration and edifice shape, Mount Rainier, Washington. Geology, 29(9), 779-782.