Special Issue: Ocean Hemisphere network Project (OHP)
- Open Access
Development of instruments for seafloor geodesy
Earth, Planets and Space volume 50, pages 905–911 (1998)
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.
Chadwell, C. D., F. N. Spiess, J. A. Hildebrand, L. E. Young, G. H. Purcell, Jr., and H. Dragert, Seafloor strain measurement using GPS and acoustics, in Gravity, Geoid and Marine Geodesy, IAG Symposia, vol. 117, edited by J. Segawa et al., pp. 682–689, Springer-Verlag Berlin Heidelberg, 1997.
Dicke, R. H., Object detection system, U.S. Patent, no. 2,624,876, issued Jan. 6, 1953.
Fujimoto, H., T. Kanazawa, and H. Murakami, Seafloor acoustic ranging and the effect of temperature variation, in Gravity, Geoid and Marine Geodesy, IAG Symposia, vol. 117, edited by J. Segawa et al., pp. 690–695, Springer-Verlag Berlin Heidelberg, 1997.
Fujimoto, H., A. Oshida, T. Furuta, and T. Kanazawa, Development of an ocean bottom gravimeter, J. Japan Soc. Mar. Sur. Tech., 10, 25–38, 1998 (in Japanese with English abstract).
Heki, K., G. R. Foulger, B. R. Julian, and C.-H. Jahn, Plate dynamics near divergent plate boundaries: geophysical implications of postrifting crustal deformation in NE Iceland, J. Geophys. Res., 98, 14279–14297, 1993.
Mackenzie, K. V., Nine-term equation for sound speed in the oceans, J. Acoust. Soc. Am., 79, 807–812, 1981.
MacWilliams, F. J. and N. J. A. Sloane, Pseudo-random sequences and arrays, Proc. IEEE, 64, 1715–1729, 1976.
Spiess, F. N., G. H. Purcell, and H. Dragert, Determination of sea floor displacements using precision transponders and GPS, in Proc. INSMAP 94, pp. 51–60, Mar. Tech. Soc., Washington, D.C., U.S.A., 1994.
Yabuki, T., Y. Nagaya, A. Asada, F. Ono, and K. Tajiri, Development of a seabottom horizontal distance meter for observation of seafloor movements, in Proc. INSMAP 94, pp. 493–498, Mar. Tech. Soc., Washington D.C., U.S.A., 1994.
About this article
Cite this article
Fujimoto, H., Koizumi, Ki., Osada, Y. et al. Development of instruments for seafloor geodesy. Earth Planet Sp 50, 905–911 (1998). https://doi.org/10.1186/BF03352186
- Crustal Deformation
- Earth Tide
- Baseline Length
- Pseudorandom Noise
- Ocean Bottom Pressure