Viscoelastic rheology and folding
Viscoelastic strain in lava flows is commonly expressed as surface folding, the mechanism responsible for the iconic ropy pahoehoe texture. This particular surface morphology preserves both a rheological and a compositional signature of the hosted lava flow.
We use quantitative morphometric analyses, such as high-resolution photogrammetry and Fourier transforms of finite topography, to solve for the complicated geometry of folded lava surfaces. In this study, we revealed a power-law relationship between fold wavelength ratios and silica content for lavas across the compositional spectrum. This has implications for remote characterization of lava flows on Earth and other terrestrial bodies in the solar system.
Mapping viscosity of active lava flows
Viscosity is a critical rheologic parameter that determines the velocity, evolution, and final morphology of active lava flows. Measuring the viscosity of a lava flow, however, is non-trivial. Viscosity can change by orders of magnitude through space and time in a given flow and is thus one of the most elusive properties of flowing lava.
I am currently examining the temporal and spatial evolution of experimental lava flows using a new technique called viscosity mapping. This integrative approach brings together time-lapse 3D photogrammetry with existing analytical rheology models to solve for the viscosity of active lava flows.
Currently under review in JGR: Solid Earth.
Predicting lava breakout location
Inflation and breakouts are two fundamental mechanisms involved in the emplacement of basaltic pāhoehoe lava flows. Lava flow breakouts occur when the fluid pressure within the molten lava core exceeds the yield strength of the overlying crust. Therefore, a relationship should exist between the loci of lava breakouts and the relative position of greatest total fluid pressure and/or weakest overlying crust. We tested this hypothesis with observations of meter-scale experimental basaltic lava lobes, using lava thickness patterns as a proxy for total fluid pressure, and surface temperature as a proxy for crustal strength.
Currently under review in Geology