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USGS Southern California GPS Network

Daniel N. Determan, Aris G. Aspiotes, Derik T. Barseghian, Kenneth W. Hudnut, & Keith F. Stark

Published August 15, 2016, SCEC Contribution #7028, 2016 SCEC Annual Meeting Poster #145

The USGS Pasadena field office now operates 140 permanent, continuously-operating Global Positioning System monitoring stations as part of the Southern California GPS Network (SCGN). The SCGN network has grown and modernized significantly over the last several years with the help of projects like the American Recovery and Reinvestment Act (ARRA), which provided funding to replace equipment throughout the network and added the capability of tracking other Global Navigation Satellite Systems (GNSS) signals, such as Russia’s GLObal NAvigation Satellite System. Another project, funded by an Urban Area Security Initiative (UASI) grant received by Caltech, provided resources for the purchase of 41 Trimble NetR9 GPS receivers and Zephyr Geodetic II antennas which have been added to the network. This new equipment supports other GNSS and it includes “on-board” Precise Point Positioning with Ambiguity Resolution (PPPAR) processing. This new capability allows the streaming of processed positions directly from the receiver, which is well-suited to support the West Coast - Earthquake Early Warning (WC-EEW) system at sites close to an active fault for determining displacements quickly after a large event. The UASI project also provided us the opportunity to co-locate GPS equipment at many newly upgraded UASI seismic stations, expanding the network from 104 to 140 stations, increasing the number of real-time stations from 95 to 130, and increasing the number of co-located seismic/GPS stations from 26 to more than 60. We process all our real-time stations using RTNet software in precise point position mode and we have partially implemented differential processing at a subset of our sites. We will be including all stations in our differential processing in the near future. The 41 Trimble NetR9 stations also compute on-board PPPAR positions using RTX software. We use both the RTX and RTNet PPPAR processing output to compare positions and for an independent solution for quality control. Our network utilizes three types of geodetic grade GPS receivers: 89 have NetG3A receivers; 10 utilize NetRS receivers; and 41 use the new NetR9 receivers with RTX software (PPPAR). In the coming year, we hope to replace the NetRS receivers and continue integrating with the Northern California GPS Network and the Southern California Seismic Network. We also plan to concentrate more on improving our data telemetry, to increase the robustness and reliability of all of our real-time data streams for EEW and other products.

Key Words
tectonic geodesy, earthquake early warning

Determan, D. N., Aspiotes, A. G., Barseghian, D. T., Hudnut, K. W., & Stark, K. F. (2016, 08). USGS Southern California GPS Network. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy