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  • Article
  • Open Access

Development of instruments for seafloor geodesy

  • 1Email author,
  • 1,
  • 1 and
  • 2
Earth, Planets and Space201450:BF03352186

  • Received: 2 April 1998
  • Accepted: 17 July 1998
  • Published:


We have developed systems for measuring differential displacements across a fault zone, and examined their resolutions through seafloor experiments at relatively short baselines. A system for a seafloor extensometer makes use of precise acoustic ranging with a linear pulse compression technique. The system has a resolution better than 1 cm in acoustic ranging over a baseline of at least 1 km. The most critical problem is correction for temperature variations, and we estimate that the effect can be corrected with cm-order accuracy in the case of a deep-sea experiment. We have also examined a leveling system on the seafloor using an array of ocean bottom pressure gauges and an ocean bottom gravimeter to detect differential vertical motion. The system is estimated to have a resolution of several centimeters in vertical displacement. These system will be useful for triangulation and leveling on the seafloor, but we need further studies over a longer baseline and to achieve better long-term stability.


  • Crustal Deformation
  • Earth Tide
  • Baseline Length
  • Pseudorandom Noise
  • Ocean Bottom Pressure