Deep-Water OBS (Ocean Bottom Seismometer) Array with Real-Time Telemetry

摘要

A two-element, ocean bottom seismometer (OBS) array, operating in the ULV/VLF range, has been developed for use at depths at 2000 meters and inter-element spacing to 600 meters Seismic periods between 1 and 200 seconds, accelerations of 10 to the minus 7th meters/sec sq, and pressure fluctuations of 1 pascal are within the system sensing limits. As such, investigations related to ambient ocean noise and low frequency ARI are possible. The array incorporates real-time radio telemetry to provide a user with on-site, quick-look capability while eliminating ship tending and/or anchoring constraints. The array features rapid deployment and retrieval and observational periods of 5 days before recharging the buoy batteries. Total length of array cable is 3020 m. Each element of the array is composed of: a three axis set of medium-period seismometers, a differential pressure gauge and, to determine package orientation, two inclinometers and a north-seeker. All sensor signals are digitized within the underwater package and a single, coaxial mooring cable couples the seismic data from each element to a surface telemetry buoy where it is relayed, via radiofrequency, to a shipboard receiver for immediate storage and real-time analysis. This report describes the system components, characteristics, and specifications.