Phase 2 of Enhancements to the OOI Cabled Array at Axial Seamount

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Axial Seamount is the most active volcano in the U.S. Pacific Northwest - it just happens to be located underwater, about 300 miles off the Oregon coast. It has erupted three times in the last 20 years, and we know it is building toward another eruption in the next few years. Consequently, it is an ideal site for long-term monitoring with the National Science Foundation's Ocean Observatory Initiative Cabled Array (OOI-CA) in the Northeast Pacific ocean, which is the world's most advanced underwater volcano observatory. Previous monitoring with the OOI-CA has shown that Axial Seamount has a very repeatable cycle of inflation and deflation that has been used to forecast eruptions. This project will deploy additional monitoring instruments at Axial Seamount over the next 5 years and these will allow us to better forecast the next eruption, will improve our models of magma is supplied and stored within the volcano, and will test ideas about the deep-sea marine environment is impacted by submarine eruptions. This research serves the national interest and society because it will improve our understanding of how volcanoes work and how eruptions can be better forecast (both on land and underwater).This project will fund modest, cost-effective, and timely enhancements to the instrumentation on the OOI Cable Array to address some deficiencies in the existing infrastructure. A key element will be deploying Conductivity, Temperature, Depth (CTD) instruments on the seafloor to measure changes in salinity to test the hypothesis that hydrothermal brines are released in the summit caldera during some eruptions. Specifically this project will: (1) keep one seafloor CTD that is already deployed operating on the OOI-CA for 5 more years, (2) add two additional seafloor CTDs at two other sites on the OOI-CA for expanded spatial coverage and needed redundancy, and (3) build eight Mini-BPR (bottom pressure recorder) sensors to replace other instruments that are part of the long-term geodetic monitoring that augments the observations from the OOI-CA. These enhancements to the monitoring effort at Axial Seamount will be available in time to be deployed during the next eruption at Axial Seamount (currently expected between 2020-2022), which will help to increase our understanding of the shallow magma supply and storage systems at active basaltic volcanoes, the processes that lead to and trigger eruptions, and the impacts of submarine eruptions on hydrothermal systems and chemosynthetic ecosystems.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.