New paper led by PhD student Amy Myers! Analogue models of lava dome growth
Another new paper from Amy Myers! In this paper, we use brand new analogue models to investigate dome growth as a function of material properties. We present new scaled analogue models that use a sand-plaster mix as a solid analogue and a syrup-sugar suspension as a fluid analogue. Our models are particularly relevant to dome growth after repose as we simulate a long-term average extrusion rate that is low relative to the cooling rate. We simulate longer periods of repose by increasing the cohesion of our solid material in the upper conduit. We analyse the data using particle image velocimetry to detect fracturing of the dome carapace.
The main conclusions of the study are: (1) modelled domes reproduce the range of aspect ratios and morphologies seen in nature; (2) analogue models with high cohesion can reproduce the very high aspect ratio spines we see in nature; (3) cohesion of material in the upper conduit exerts the largest control on first order geometric parameters; (4) viscosity plays a minor role; and (5) dome deformation is influenced by the interplay between solid and fluid dynamics, where fracturing of the carapace controls formation of pathways for fluid to reach the dome surface.
Figure 10 from Myers et al. (2024). Log-log plot of height and width measurements from viscous extrusions. Grey circles show natural domes and grey triangles show spines as classified in literature (from Myers et al., 2024). Coloured filled points show the final geometry in each experiment from this study, shown only as a function of cohesion for sand (orange circles), sand with 10 % gypsum (blue diamonds) and sand with 20 % gypsum (green triangles). Hollow symbols show maximum spine dimensions from short-lived spines for 10 % gypsum (diamonds) and 20 % gypsum (triangles). Grey squares show dimensions from previous viscoplastic analogue models (Blake, 1990; Griffiths and Fink, 1993; Griffiths and Fink, 1997). Dashed grey lines represent lines of equal aspect ratio. Note that despite the difference in absolute height and width values, modelled and natural extrusions have similar height-width aspect ratios and thus possess geometric similarity.
