SCEC Award Number 21026 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Development of GNSS auxiliary time series products and velocities for the CGM; and post-Ridgecrest survey GNSS data analysis
Investigator(s)
Name Organization
Michael Floyd Massachusetts Institute of Technology Thomas Herring Massachusetts Institute of Technology
Other Participants
SCEC Priorities 1a, 2a, 3e SCEC Groups CXM, Geodesy, SDOT
Report Due Date 03/15/2022 Date Report Submitted 11/12/2024
Project Abstract
 Our project fulfilled two tasks, one related to the continued development and dissemination of the Community Geodetic Model (CGM) and a second related to extending GNSS time series after the July 2019 Ridgecrest earthquakes using field data collected by other SCEC researchers. We have developed, along with SCEC IT, the CGM web page and Explorer for browsing both GNSS and InSAR products which have been generated to date and are now publicly available. We have extended the post-Ridgecrest survey GNSS time series using the data collected in the field by Gareth Funning (UC Riverside) throughout 2021, plus previous data from Scripps Institution of Oceanography, the Nevada Geodetic Laboratory and the US Geological Survey. These time series will prove invaluable for the densification of GNSS measurements in the near-field of the earthquake ruptures.
Intellectual Merit The Community Geodetic Model is a core component of SCEC's goals for both the scientific community and public. Our contributions are largely focused on understanding variations between GNSS products made available by analysis centers and, where different, what the most appropriate corrections and ultimate products might be to be most useful to the community at large. We are also engaged regularly with similar research generating InSAR products within the CGM Working Group, which is similarly doing active research on the variety of techniques and corrections to apply to produce InSAR time series and dense velocity maps. Finally, we are engaged the continued collation, translation and processing of GNSS data following the July 2019 Ridgecrest earthquakes which, in addition to products from continuous GNSS sites, densifies the GNSS data available for constraining models of the aftermath of this large event in southern California.
Broader Impacts In association with this project, we organized and held a workshop dedicated to the CGM at which we demonstrated, to a large audience of around 70 participants, the current status of the CGM. This included a summary of active research and products currently available, including how to access them. We actively encouraged students to participate and consider how the CGM may be useful to their research and encouraging everyone to consider how their research may be incorporated into the CGM. The CGM (InSAR) Working Group continues to hold virtual meetings every two weeks and a significant proportion (nearly all) of this group are current graduate students or early-career scientists. Our activities ensure that geodetic (GNSS and InSAR) are centralized and available to the community, which eventually will be incorporated into a model framework. We anticipate results from this will be a key input or constraint to other CXMs, for example geodetically derived strain rate for the Community Rheological Model.
Exemplary Figure Figure 2: Example post-earthquake time series from two survey marks which have been measured regularly, mostly by Gareth Funning (UC Riverside), since the July 2019 Ridgecrest earthquakes (orange dashed line “49”), plotted relative to their pre-earthquake velocities to show post-seismic deformation.
[M. Floyd, MIT]
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