USGS Global Positioning System (GPS) Network in Southern California

Daniel N. Determan, Aris G. Aspiotes, Christian Guillemot, John O. Langbein, Mark Murray, Marcos Alvarez, & Keith F. Stark

Submitted August 15, 2017, SCEC Contribution #7728, 2017 SCEC Annual Meeting Poster #093

The USGS Pasadena office operates 141 permanent, continuously-operating GPS monitoring stations as part of the Southern California GPS Network (SCGN). The SCGN network has grown and modernized over the years with the help of American Recovery and Reinvestment Act (ARRA) funds and an Urban Area Security Initiative (UASI) grant received by Caltech. These funds allowed for the purchase of new equipment with new capabilities, such as tracking other Global Navigation Satellite Systems (GNSS) signals and having the ability to process "on-board" Precise Point Positioning with Ambiguity Resolution (PPPAR). The on-board PPPAR allows the streaming of processed positions directly from the receiver. This 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 seismic event. The UASI project also provided us the opportunity to co-locate GPS equipment at newly upgraded UASI seismic stations, expanding the network from 104 to 141 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 64. We process our real-time stations using RTNet software in precise point position mode and we have partially implemented differential processing that will be fully implemented in the near future. The 41 sites with Trimble NetR9 receivers also compute on-board PPPAR positions using Trimble's 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 currently utilizes three types of geodetic grade GPS receivers: 90 have NetG3A receivers; 10 utilize NetRS receivers; and 41 use the new NetR9 receivers with on-board RTX software (PPPAR). In the coming year, we intend to continue our integration with the Northern California GPS Network and the Southern California Seismic Network. We will also concentrate on improving our data telemetry, to increase the robustness and reliability of all of our real-time data streams for EEW and other real-time data products.

Key Words
geodesy, crustal deformation, Earthquake Early Warning

Citation
Determan, D. N., Aspiotes, A. G., Guillemot, C., Langbein, J. O., Murray, M., Alvarez, M., & Stark, K. F. (2017, 08). USGS Global Positioning System (GPS) Network in Southern California. Poster Presentation at 2017 SCEC Annual Meeting.


Related Projects & Working Groups
Tectonic Geodesy