SCEC Award Number 21025 View PDF
Proposal Category Workshop Proposal
Proposal Title SCEC Community Geodetic Model Workshop
Investigator(s)
Name Organization
Michael Floyd Massachusetts Institute of Technology Ekaterina Tymofyeyeva National Aeronautics and Space Administration
Other Participants David Bekaert
Eric Fielding
Gareth Funning
Alejandro González Ortega
Katherine Guns
Thomas Herring
Xie Hu
Zhen Liu
Kathryn Materna
Jessica Murray
David Sandwell
Zheng-Kang Shen
Kang Wang
Xiaohua Xu
SCEC Priorities 2a, 1a, 3e SCEC Groups CXM, Geodesy, SDOT
Report Due Date 12/10/2021 Date Report Submitted 12/14/2021
Project Abstract
 The Community Geodetic Model (CGM) is a SCEC community effort to research and develop best practices for geodetic displacement time series, velocities and derived strain rate fields, from both GNSS and InSAR, which are made available to the scientific community for application to earthquake and other geophysical studies throughout southern California. This was the third CGM Workshop held during SCEC 5, approximately every two years, to disseminate information on progress by the CGM Working Group to the broader community and gain feedback from the community on their needs and potential contributions. Many contributors are already funded by SCEC but many others in the community have developed or are developing methods which would be directly applicable or generally helpful to the CGM efforts. Furthermore, the CGM is ultimately designed to facilitate users of geodetic data without having to be geodetic data experts themselves, so outreach to potential users was and is a critical component of this and past workshops.
Intellectual Merit The Community Geodetic Model is a critical component of the suite of Community Models. The CGM has brought together many geodetic experts from various institutions around the US and beyond, many of whom supply operational products of their own to the combination. SCEC has played a central role, in this sense, with the creation of a set of InSAR time series. This product and the combination of the GNSS and InSAR time series and velocities are also unique aspects of the CGM in western North America.
Broader Impacts The major requirements raised by potential users, and, we hope, answered by our contributions, tend to regard the variations apparent in the many geodetic products available from other institutions, and how these can be understood and reconciled. The Community Geodetic Model is therefore a key forum for the education of the (non-expert) user community regarding the various choices made during generation of geodetic products, how these may affect the time series and associated uncertainties provided in the products, and how these may (and should) be treated (with caution) when used in models, depending on the type of modeling. For example, the reference frame for the vertical component of time series, and its propagation to comparing, contrasting and interpreting signals associated with surface loading, for example atmospheric and hydrologic. The “distillation” of complex data by experts for the ready use of the scientific community and the public is central to SCEC’s mission.
Exemplary Figure Figure 1: The InSAR and GNSS CGM velocity models, as shown in the CGM web viewer. Blue circles represent the locations of the continuously-recording GNSS stations. The InSAR velocities are in the descending line of sight.