Observations of Seafloor Vertical Deformation on Axial Seamount with the Self-Calibrating Pressure Recorder

Abstract:

A geodetic pressure gauge, the Self-Calibrating Pressure Recorder (SCPR), was deployed on Axial Seamount on September 7, 2013. The device performs in situ pressure calibrations every 10 days by applying a time-invariant reference pressure from a piston gauge (also known as a deadweight calibrator) to continuously recording quartz pressure gauges through a hydraulic valve. The reference pressure measurements are then used to estimate and correct for the inherent drift in the quartz resonant seafloor pressure gauges. Pressure data are collected at 100 s integration intervals. A small subset of a year-long data set was recovered via an acoustic modem in August 2014. Using three epoch measurements, the pressure rate of change from September 2013 to August 2014 was -4.1 to -4.2 kPa/year, equivalent to uplift of 41- 42 cm/year. Other pressure time series and micro-bathymetric repeat surveys are in rough agreement with this SCPR rate. The instrument is scheduled for recovery in August 2015; the anticipated data collection interval spans the eruption on April 24, 2015. We present the drift-corrected pressure series and constraints estimated for magma supply rates during the inflation, eruption, and post-eruptive phases.