Construction and Deployment of a Seafloor Drift-Corrected Pressure Gauge for Deformation Observation at Axial Volcano

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Geodesy plays an important role in gaining understanding of the tectonics that shape Earth?s crust. Subaerial geodesy is a mature, advanced science. Submarine geodesy, on the other hand, limited by the opacity of seawater to electromagnetic radiation, is relatively new and is still in need of alternate techniques to detect seafloor deformation reliably. Acoustic methods to observe horizontal deformations of the seafloor have been successful, but the deep ocean sound velocity structure prohibits the technique from being useful in the vertical dimension. Fortunately, seawater pressure measurements provide a method to observe changes in vertical position with centimeter precision. A key factor, however, limits the ability to infer vertical deformation from seawater pressure change: the ever present and unpredictable drift in pressure gauges. The PI?s have designed and tested a laboratory prototype for a piston gauge pressure reference (PGPR). The prototype has a demonstrated repeatability equivalent to 0.5 cm of vertical deformation at a simulated depth representative of a mid-ocean ridge. The PI?s request funding to construct and deploy such an instrument on the seafloor to provide a means to remove drift from geodetic pressure gauges and allow observation of secular variation in seafloor height. Broader Impacts Development of new technologies for underwater geodesy is a needed step to further our understanding of processes along the several 10,000's km of submerged plate boundaries; it would also help with monitoring incipient landslides along the margins. It is therefore a critical field of research for the assessment of natural hazards in coastal areas.