A Method for Magma Viscosity Assessment by Lava Dome Morphology

Abstract Lava domes form when a highly viscous magma erupts on the surface. Several types of lava dome morphology can be distinguished depending flow rate and rheology magma: obelisks, lobes, endogenic structures. The viscosity nonlinearly depends volume fraction crystals temperature. Here we present an approach to estimation based comparison observed simulated morphological forms domes. We consider two-dimensional axisymmetric model extrusion surface evolution, assume that only crystals. crystallization is associated with growth liquidus temperature due volatile loss from magma, it determined by characteristic time crystal content (CCGT) discharge rate. are modeled using finite-volume method implemented in Ansys Fluent software for various CCGTs volcanic vent sizes. For selected eruption duration set shapes (shapes interface between air) obtained. this way compared shape (synthesized study random modification one calculated shapes). To estimate viscosity, deviation assessed three functionals: symmetric difference, peak signal-to-noise ratio, structural similarity index measure. These functionals often used computer vision image processing. Although each functional allows determine best fit dome, measure performs better. then approximated which fits dome. This extended three-dimensional case studies restore conditions natural growth.