Open Access

Development of instruments for seafloor geodesy

  • Hiromi Fujimoto1Email author,
  • Kin-ichiro Koizumi1,
  • Yukihito Osada1 and
  • Toshihiko Kanazawa2
Earth, Planets and Space201450:BF03352186

https://doi.org/10.1186/BF03352186

Received: 2 April 1998

Accepted: 17 July 1998

Published: 6 June 2014

Abstract

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.