New Opportunities in Passive Seismic Acquisition

John A. Orcutt*, Jonathan Berger, Jeff Babcock

Institute of Geophysics & Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego

We have developed and extensively tested technologies that support long-term, seafloor observations with great fidelity. Seafloor noise levels, in quiet seas, are comparable to observations on the best continental and island installations. The quality of data can be substantially enhanced by autonomous seafloor burial and the use of new broadband seismometers and DPGs. Coupled with autonomous surface vehicles (ASVs), near real-time seafloor data can be transferred via acoustics and Iridium satellite communications. Latency; that is, the time of receipt of a group of data at the shore side facility minus the time of the oldest datum in that group is dominated by the sum of the digitizer group delay, the time to gather a group of data to telemeter, the time to send the data through the water column and the time to send the data through the satellite network. Overall analysis of 68 days of operation shows median total system latency of 260s. The largest contribution to the total latency involved establishing a connection through Iridium. Telemetry can be enhanced significantly by the use of Low/Medium Earth Orbit (LDEO/MEO) Small Sats. In the future these new technologies will significantly reduce ship costs while providing a means for interacting with the remote seafloor packages to ensure data quality and provide the means for remote maintenance. The technologies will support a global distribution of the Global Seismic Network (GSN) and passive/active arrays and networks for Earth structure, earthquake source studies as well as nuclear test and tsunami detection.