Updating GPS site positions and velocities and improving GPS coverage in southern California for the Community Geodetic Model

Eneas Torres Andrade, Gareth Funning, & Jerlyn L. Swiatlowski

Submitted August 15, 2018, SCEC Contribution #8755, 2018 SCEC Annual Meeting Poster #137

We have conducted a GPS resurvey of geodetic benchmarks in the Inland Empire of southern California, with the goal of more precisely determining the rates of movement of the major strike slip faults in the region – the San Andreas, San Jacinto and Elsinore faults. The gathering and processing of the acquired GPS data from these geodetic benchmarks will ultimately provide updated and more precise GPS velocities, which will in turn lead to better constraints on modeled fault slip rates. In addition, new campaign GPS surveys provide the opportunity to add additional campaign sites that can, with time and with additional measurements, yield new velocity estimates. Finally, GPS resurveys can help to maintain memory of locations of GPS benchmarks, and hence improve our ability to respond promptly to earthquakes.

To conduct the survey we used three high precision GNSS receivers and antennas (Trimble R7 receivers and Trimble Zephyr Geodetic antennas) to log GPS satellite measurements. Benchmarks were typically occupied overnight, yielding observations spanning 15 hours or longer. The resulting raw data were preprocessed into the RINEX file format using the runpkr00 and teqc software. Next, the resulting RINEX files were processed using the GAMIT processing suite to update or estimate new GPS positions of the surveyed benchmarks, and also to check the quality of the data. In total, we occupied 26 benchmarks over a 10 week period. We added a total of six new benchmarks – two in the Cajon Pass area and three in Whitewater Canyon near the San Andreas fault, and an additional one near the San Jacinto fault, improving the density of GPS coverage in the region. We also surveyed sites measured for the first time by past SCEC interns and updated the positions from these sites, adding a total of three new velocities.

Key Words
Geophysics, Geodesy, GPS

Citation
Torres Andrade, E., Funning, G., & Swiatlowski, J. L. (2018, 08). Updating GPS site positions and velocities and improving GPS coverage in southern California for the Community Geodetic Model. Poster Presentation at 2018 SCEC Annual Meeting.


Related Projects & Working Groups
Tectonic Geodesy