SCEC Award Number 24065 View PDF
Proposal Category Collaborative Research Project (Multiple Investigators / Institutions)
Proposal Title Statewide expansion of the GNSS component of the Community Geodetic Model and associated earthquake response products
Investigator(s)
Name Organization
Michael Floyd Massachusetts Institute of Technology Thomas Herring Massachusetts Institute of Technology Alejandro Gonzalez-Ortega Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Mexico)
SCEC Milestones A1-1, A3-5, A3-6 SCEC Groups CEM, Geodesy, SDOT
Report Due Date 03/15/2025 Date Report Submitted 04/02/2025
Project Abstract
 We have expanded the region over which the Community Geodetic Model (CGM) continuous GNSS time series products are available, using the same methodology as we have previously for southern California, to include the whole of California and northern Baja California in Mexico. We have also begun to incorporate survey GNSS solutions from northern California from various sources of time series or raw data, a significant portion of which we have reprocessed ourselves in the past or recently. We continue to identify and attempt to resolve inconsistencies between the analysis centers' products which comprise the CGM (GNSS) products. We have also attempted to update records for the SCEC GNSS equipment pool in preparation for any earthquake response event.
SCEC Community Models Used Community Geodetic Model (CGM)
Usage Description This award contributes organization, presentations and developing products for the Community Geodetic Model. No other SCEC Community Model *outputs* were used as *inputs* to research during this award.
Intellectual Merit This award supports a core element of SCEC, the Community Earth Models, specifically the GNSS component of the Community Geodetic Model. Our efforts provide a consensus set of GNSS time series and velocity, which are aligned and merged from several independent sources, for use by the SCEC community. We investigate discrepancies between the ingested solutions to describe and explain to the SCEC community the pros and cons, limitations and caveats of each individual solution and the consensus solution so that the community can be best informed about their use in geophysical analyses.
Broader Impacts The CGM is a community-wide exercise and the knowledge acquired through the development of the GNSS component is critical to the proper understanding and appropriate use of GNSS products in the SCEC community's research. It is also important to maintain the visibility (and viability) of survey GNSS data within the community's consciousness and skills, in addition to continuously recorded data, given the role that post-earthquake surveys have and can play in response to events. Our work contributes to the availability of and learning about GNSS data via the SCEC CGM Explorer.
Project Participants Mike Floyd and Tom Herring (MIT), and Alex Gonzalez-Ortega (CICESE) contributed to this project. Significant work was funded additionally by the USGS and GAGE (EarthScope; formerly UNAVCO). Analysis centers providing (publicly available) GNSS solutions to the CGM (GNSS) products are GAGE, NASA/JPL, NGL/UNR, SOPAC (MEaSUREs) and the USGS. Zheng-Kang Shen (UCLA) processed and provided survey GNSS time series for southern California through SCEC-related work in previous years.
Exemplary Figure Figure 1: Direct comparison of time series from three analysis centers, GAGE (blue), NGL/UNR (green) and NASA/JPL (red).
Linked Publications

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