Collaborative Research: BENEATH THE FOUNTAINS: Shallow conduit processes and diversity in basaltic fissure eruptions.

Mildly explosive eruptions—the most frequent manifestations of subaerial explosive volcanism on Earth—broadly group into two styles: Strombolian and Hawaiian. The former is characterized by sequences of intermittent discrete explosions and the latter by sustained pyroclastic fountaining. Explosive activity during the 2018 fissure eruption of Kīlauea volcano (Hawaiʻi) provided an exceptional opportunity to record a wide range of Strombolian and Hawaiian behavior (Figure 1), thanks to the accessibility of the volcano and the wealth of data types collected throughout the event. This study address which processes in the plumbing system beneath the volcano 'drove' the great diversity in style and intensity of the 2018 explosive activity compared to previous, more consistent, fissure eruptions at Kīlauea and elsewhere? Kīlauea is an exceptionally active volcano and its eruptions pose constant challenges for management agencies because the eruption sites are highly accessible and there is a need to balance the strong popular interest in viewing the eruptive activity against public safety (as seen in 2018). This balance requires critically on sophisticated knowledge of the volcano's current and immediately future behavior. There is both a public desire for better knowledge of the volcano's behavior and a need for improved forecasting of the likely course and footprint of all future eruptions. The observatory partner, USGS, has a federally mandated role to advise response agencies in Hawaii and will transfer knowledge from the NSF-funded study to the bodies charged with risk management. This work involves exchange of material and ideas between institutions in the USA, and the United Kingdom to the benefit of young researchers and students. The results will be widely disseminated via meetings and workshops, courses offered by the FEMA-funded National Disaster Preparedness Training Center, the Internet and scientific publications and a planned virtual field trip to Kilauea.

The goal of this study is to link existing high-resolution observations of explosive basaltic fissure eruptions to the processes in the very shallow conduit that cause and shape them, focusing on the 2018 Kīlauea eruption as a case study. It will combine existing data derived from high temporal and spatial resolution videos with: (1) field measurements of five representative pyroclastic footprints, and laboratory characterization of the ejecta, (2) high-precision measurements of two-phase magma rheology, and (3) models tied to newly completed laboratory analog experiments to simulate outgassing patterns. This approach is expected to help identify patterns and precursors that accompany transitions in eruptive style, supporting risk management for communities on the flank of this very active volcano. This study will fundamentally improve our understanding of the dynamics of Hawaiian and Strombolian eruptions.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.