Instrument development for geophysical monitoring at cabled seafloor observatories

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The PI requests funding to adapt existing geophysical instruments to operate on a fiber optic cable network. The adapted instrument package will be tested on the MARS cable for six months, and afterward will be ready to deploy on US Neptune, at the proposed node site at Axial Seamount. The instrument package will include a bottom pressure recorder (BPR) and a precision tiltmeter, both designed to monitor inflation or deflation in submarine volcanic areas caused by magma movements underground. The technical challenge of this project is to develop the power and data communication schemes required to convert these autonomous, battery-powered, and internally recording instruments to fully embedded, interactive instruments on a fiber-optic network. The proposed work builds on previous successful (non-cabled) monitoring efforts at Axial Seamount, which show that it is currently inflating at 10-20 cm/yr and is building toward its next eruption. The scientific goal is to better understand volcanic cycles at active submarine volcanoes by quantifying magma supply rates and discovering how they vary over time.Broader Impacts: The proposed sensor package will represent an important component to the eventual system that will allow for a deeper understanding of the geophysical processes at the OOI/RSN site. On its own, the proposed project will provide important guidance in the development of other cabled systems employing these (and other) cabled sensors. The fact that the University has agreed to support a graduate student in the conduct of the proposed project ensures that the project will contribute to the education of ocean observation professionals. Additional aspects of future interest include Axial's time-series inflation/tilt comparisons with similar work proposed at 9 50' N on the EPR. There is also potential value added by similar equipment deployments in subduction zones and methane hydrate areas off the Pacific NW, as well as in tsunamigenic areas where such instruments can augment natural hazards work. There is much potential public access to these data that the PI seems willing to provide.