Experimental Constraints on the Rheology of Lavas From 2021 Cumbre Vieja Eruption (La Palma, Spain). Issue 4 (14th February 2023)

• Record Type: Journal Article
• Authors: Di Fiore, F.; Vona, A.; Scarani, A.; Giordano, G.; Romano, C.; Giordano, D.; Caricchi, L.; Martin Lorenzo, A.; Rodriguez, F.; Coldwell, B.; Hernandez, P.; Pankhurst, M.
• Is Part Of: Geophysical research letters. Volume 50:Issue 4(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-14
• Subjects: rheology -- lava flow -- Cumbre Vieja -- crystallization kinetics -- cooling rate -- stirring; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL100970
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The 2021 Tajogaite eruption of Cumbre Vieja (La Palma, Spain) was typified by the emission of low viscosity lavas that flowed at high velocities and inundated a large area. We experimentally investigated the rheological evolution of melt feeding the eruption through concentric cylinder viscometry to understand the exceptional flowing ability of these lavas and constrain its emplacement dynamics. We conducted a set of cooling deformation experiments at different cooling rates (from 0.1 to 10 °C/min), and isothermal deformation experiments at subliquidus dwell temperatures between 1225 and 1175°C. All experiments were conducted at a shear rate of 10 s −1 . Results show that disequilibrium crystallization and its timescale fundamentally control the rheological evolution of the melt, resulting in different rheological response to deformation of the crystal‐bearing magmatic suspension. Integrating rheological data with field observations allows us to shed light on the mechanisms that govern the high flowability of these lavas. Plain Language Summary: Understanding and modeling the mechanisms controlling the inundation ability of lava flows is pivotal for hazard assessment and mitigation of related risk. Lavas flowing across the Earth's surface experience different cooling conditions. These conditions are related to the thermal gradients generated at various levels within the flow's thickness. Especially for extremely fluid magmas such as those erupted at Cumbre Vieja, the different cooling paths (and different disequilibrium conditions) that lava flows experience strongly influence the crystallization processes. Both cooling and crystallization produce an increase of lava viscosity, hindering lava flowability. If crystallization occurs over timescales shorter than those of cooling, the presence of crystals may give rise to more complex flow behavior and emplacement style, including flow rupture and separation. Such conditions may favor the development of flow decoupling and lava tunnel formation. In this study we experimentally investigate the viscosity evolution of the Tajogaite lavas and the transition from pure viscous flow to more complex responses to deformation. Then, we use our data set in concert with field observation to constrain the dynamics governing the emplacement style of these lavas. Key Points: High‐ T deformation experiments characterize the rheology of Cumbre Vieja lavas under both disequilibrium and equilibrium conditions Two different rheological responses are observed in relation to the increased disequilibrium conditions at which the melt is subjected Integration of experimental and field data permits to understand the mechanisms that enhance the flowing ability of these lavas