A lower bound on the rheological evolution of magmatic liquids during the 2018 Kilauea eruption

During the four month-long 2018 Kilauea Lower East Rift Zone (LERZ) eruption, the bulk chemical compositions of magma ranged from basalt to andesite. This compositional variety was reflected in eruptive style, which ranged from Hawaiian fountaining to Strombolian explosions. Here, we quantified the evolution of the melt viscosity of the eruptive products through high-temperature laboratory experiments performed on a representative sample set that was collected in the field immediately after the eruptive series. This suite of 18 samples comprises all major eruptive phases (early phase I, late phase I, phase II, phase III, fissure 17). The results illustrate the significant rheological variability of the eruptive products, and appear to link to variations in eruption dynamics. We propose a new standard for the rheological study of a multi-episode effusive eruption, whereby precise, near-real-time viscosity results are obtained during ongoing eruptions will become a routine component of volcano monitoring during future eruptive events. Plain language summary: During the 2018 eruption of Kilauea, emerging magma spanned a wider compositional range than ever previously observed during a single eruption. This compositional diversity was matched by a variety in eruptive styles, which ranged from more persistent fountaining to short-lived explosions. Immediately after the eruption ceased, we collected a representative suite of 18 samples in the field, which comprises all major eruptive phases (early phase I, late phase I, phase II, phase III, fissure 17). We measured the melt viscosity of such samples through high-temperature laboratory experiments. The results illustrate a significant variability in viscosity, which is linked to the highly variable eruption dynamics. Here we propose a new standard for the study of multi-episode effusive eruptions from a viscosity standpoint. We hope and expect that this methodology will become routine practice during future eruption.

Automated summary

During the 2018 Kilauea eruption, magma composition varied greatly from basalt to andesite, leading to different eruptive styles from fountaining to explosions. By collecting 18 representative samples immediately after the eruption and conducting high-temperature laboratory experiments, the study quantified the evolution of melt viscosity, showing a significant variability linked to eruption dynamics. A new standard for studying multi-episode effusive eruptions from a viscosity standpoint was proposed, aiming to make viscosity measurements during ongoing eruptions a routine part of volcano monitoring in the future.