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Introduction

Unlike Ocean-Bottom Cables (OBCs), in which receivers are strung on a cable, Ocean-Bottom Seismometers (OBSs) package the receivers as individual units. While OBCs do not go deeper than 1500m, OBSs are routinely operated at depths down to 6000m, which makes them the only currently available option for recording 4-C (three-component geophone plus hydrophone) data above deepwater reservoirs. They have been continuously developed and are currently employed by the crustal seismology research community, but only occasionally by the seismic industry. I became acquainted with the Japanese OBS technology during a crustal seismology cruise[*] and I present its state-of-the-art to the seismic industry readers.

I describe the short-period OBS model developed at the University of Tokyo in the early 90's, owned by Japan Marine Science $\&$Technology Center (JAMSTEC) and currently operated and improved by Nippon Marine Enterprises Ltd. (NME). I refer to it as the ``Japanese OBS''. I selected it among the 14 OBS models known to me because of several factors that make it interesting to a seismic industry audience: like an OBC, it has 4-C recording capability in the frequency band of active seismic surveys, but unlike an OBC, it can operate at depths down to several thousand meters. Additionally, I considered for my selection the criteria of logistical robustness[*] and of extremely high reliability[*] proven in hundreds of deployments of a uniform pool of instruments.


next up previous print clean
Next: The Japanese OBS Up: Vlad: Ocean-bottom seismometers Previous: Vlad: Ocean-bottom seismometers
Stanford Exploration Project
7/8/2003