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

Abstract

Abstract 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 unusual compositional variety (for a single eruption of a shield volcano) was reflected in eruptive style, which ranged from Hawaiian fountaining to Strombolian explosions. Here, we have quantified the evolution of the melt viscosity of these 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 17 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 be linked 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 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 variety was matched by a variety in eruptive styles, which ranged from more gentle fountaining to more violent explosions. Immediately after the eruption ceased, we collected a representative suite of 17 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 directly 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.