SCEC Award Number 24178 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Updating GNSS site positions along the San Andreas Fault System in support of the Community Geodetic Model and in preparation for future earthquakes
Investigator(s)
Name Organization
Gareth Funning University of California, Riverside
SCEC Milestones A3-5, A3-6 SCEC Groups Geodesy, CEM, SDOT
Report Due Date 03/15/2025 Date Report Submitted 03/19/2025
Project Abstract
 The goal of this project was to conduct field GNSS surveys in both southern and central California to improve coverage and precision of existing GNSS velocities by making additional measurements in areas where the existing data is sparse, imprecise or contains a critical data gap. The data will be contributed to the Community Geodetic Model (CGM), and will ultimately be used to improve estimation of geodetic fault slip rates, and potentially expedite future earthquake response fieldwork in the event of an earthquake in our study area. We targeted several areas: (i) the Parkfield/Cholame area; (ii) the Cajon Pass and Mojave segments of the
San Andreas fault; and (iii) the Inland Empire and Coachella Valley. In total, we occupied 34 survey benchmarks during the project, including 13 site that we measured for the first time. The fieldwork was conducted by a SCEC SURE undergraduate intern, Rigoberto Rincon, who also did some basic GNSS data processing as a quality assurance check, under the supervision of UCR graduate student Karlee Rivera and the PI.
SCEC Community Models Used Community Geodetic Model (CGM)
Usage Description The data collected here will enable an update to the GNSS velocites in the CGM.
Intellectual Merit The data collected in this project have improve coveraged and precision of existing GNSS velocities by making additional
measurements in areas, such as the Parkfield area and Inland Empire, where the existing data is sparse, imprecise or contains a critical data gap.
Broader Impacts GNSS velocities are critical inputs into seismic hazard models, such as the National Seismic Hazard Model and the Uniform California Earthquake Rupture Forecast. They measure the deformation caused by the moment rate deficits along active faults in the interseismic phase of the earthquake cycle, and can be used to estimate geodetic slip rates. In the subsequent occurrence of an earthquake, interseismic deformation rates can be used to estimate pre-event positions so that displacements of the earthquake, and of any postseismic deformation that follows, can be accurately determined with subsequent remeasurements. Updating survey measurements can also significantly expedite post-earthquake response.
Project Participants Gareth Funning (PI)
Karlee Rivera (Graduate Student)
Rigoberto Rincon (SURE Intern)
Exemplary Figure Figure 1: Maps of areas and GNSS benchmark sites measured in this project. Three areas, Parkfield-Cholame (PK), Cajon Pass (CP) and Inland Empire/Coachella Valley (IE) were the targets of our survey efforts; we measured 34 sites in total (white triangles), in the vicinity of the San Andreas and San Jacinto faults (gray lines).
Linked Publications

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