Collaborative Research: RAPID: Study of the April 2025 Eruption at 9 50 N EPR: Fluid Pathways, Crustal Permeability, and Plume Evolution

On April 29, 2025, scientists observed molten lava erupting on the deep seafloor at the East Pacific Rise. This RAPID project will investigate the hydrothermal vent system at the eruption site. Field work includes high-temperature fluid and temperature sampling. These measurements will extend an existing time series (6 expeditions from 2018-2025) with post-eruption (within one year) data. The project will result in a unique data set for understanding hydrothermal vent evolution. Broader impacts include training opportunities for early-career scientists and a live at-sea webinar with K-12 classrooms. The work leverages a scheduled field program at the study site in January 2026 that will include geology and biology science teams. This project benefits the US public by helping to understand volcanic eruptions and helps to build a workforce knowledgeable in cutting-edge deep-sea exploration technology. This project will advance understanding of how submarine eruptions reorganize subsurface permeability, fluid pathways, and chemical exchange between the crust and the ocean. High-temperature fluid sampling will be paired with in situ temperature measurements to provide a multidisciplinary view of post-eruptive vent evolution. These samples will constrain post-eruption conditions, including phase separation, redox, and volatile budgets, while geothermobarometric and isotopic data will link these changes to permeability shifts. Integrating these data with long-term temperature and permeability records will improve models of magmatic-hydrothermal coupling and refine the ability to predict mid-ocean ridge eruptions and their impact on the ocean. 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.