Drift Corrected Seafloor Pressure Observations of Vertical Deformation at Axial Seamount 2018–2021

TitleDrift Corrected Seafloor Pressure Observations of Vertical Deformation at Axial Seamount 2018–2021
Publication TypeJournal Article
Year of Publication2023
AuthorsSasagawa, GS, Zumberge, MA, Cook, MJ
JournalEarth and Space Science
Keywordsinstruments and technique, ocean observatories and experiments, standards and absolute measurements, submarine tectonics and volcanism, volcano monitoring

Axial Seamount is a seafloor volcano with frequent eruptions and periodic cycles of inflation and deflation. Seafloor pressure gauges monitor vertical deformation with time, but inherent instrumental drift complicates and biases geodetic interpretation. A drift corrected pressure recorder was deployed on Axial Seamount on 6 July 2018, at coordinates 45° 57.29′ North latitude, −130° 0.56′ East longitude, depth 1,535 m. This system includes two independent quartz-resonant pressure gauges, which nearly continuously observe the seafloor pressure. At regular intervals, the gauges are calibrated in situ with a modified deadweight tester at a pressure within 98% of the nominal seafloor pressure. Using the calibration data, the drift of each gauge has been modeled as a simple linear plus decaying exponential function of time. The two estimated linear sensor drift rates are 0.45 ± 0.12 and 0.36 ± 0.08 kPa/year; the modeled sensor drift represents a significant error if uncorrected. The standard deviations of the drift model residuals are of order 0.06 kPa or 6 mm depth equivalent. Once calibrated, the difference between the two seafloor pressure timeseries exhibits a RMS deviation of ±6 mm at the 90% confidence limit and a linear trend less than 1 mm/year. A time series from July 2018 to December 2021 tracks the inflation of Axial Seamount with differing inflation rates over different time intervals.