Technological Advances in Autonomous Ocean Bottom Seismometry

Bruce Townsend*1, Jeff Babcock2, John Orcutt3, Ted Somerville4, Martin Rapa5

1Chief Technology Officer, Nanometrics Inc, Canada (brucetownsend@nanometrics.ca), 2Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA, 3Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA, 4Ocean Bottom Products, Nanometrics Inc, Canada, 5Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA.

Autonomous Ocean Bottom Seismograph (OBS) systems, in contrast to surface terrestrial seismic stations, have inherent limitations imposed by the deep ocean environment they operate in and related technology constraints. The size and weight of the highest performance land-based seismometers and the need for leveling gimbal mechanisms limit their use in OBS applications. The greater power consumption of high-performance seismometers, digitizers and dataloggers force trading off between seismic monitoring performance, constraints in instrument package size/weight, and deployment duration of experiments. The ad-hoc nature of merging land-based technologies for submarine use has led to procedural complexity and labor-intensive workflows in configuring complete seismic systems for ocean bottom deployments, clock synchronization and accuracy pre- and post-deployment, and harvesting and managing data and metadata upon system retrieval.

Recent research and development in highly efficient coupled seismometer / digitizer design, new workflow approaches for efficient deployment, retrieval and data management, and advances in sled design offer the promise of achieving ocean-bottom seismic monitoring performance comparable to land-based stations, simultaneously extending deployment duration, reducing cost of ship time and system management, and increasing reliability. New advances in ultra-low power miniaturized broadband seismometers that will achieve GSN performance specifications, low-power high-dynamic range digitizing technologies design for marine applications, system workflows designed for at-sea usage, and advances in overall OBS package design are presented.

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