SCEC Award Number 17103 View PDF
Proposal Category Workshop Proposal
Proposal Title Community Geodetic Model Workshop
Investigator(s)
Name Organization
Jessica Murray United States Geological Survey David Sandwell University of California, San Diego Gareth Funning University of California, Riverside Rowena Lohman Cornell University
Other Participants
SCEC Priorities 2a, 1a, 3e SCEC Groups SDOT, CXM, Geodesy
Report Due Date 04/13/2018 Date Report Submitted 05/31/2018
Project Abstract
 The Community Geodetic Model (CGM) will consist of crustal motion time series and derived products with high spatial and temporal resolution for use in a variety of SCEC research on interseismic strain rates, postseismic processes, environmental (e.g., hydrological) contributions to deformation, spontaneous slow fault slip, and other transient phenomena. The CGM is designed to leverage the complementary spatio-temporal characteristics of Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data. A major component of the project is the evaluation of existing approaches and development of new methods to incorporate multiple data sets and data types into self-consistent geodetic data products. This is an ongoing project involving a progression of steps to go from raw data to the targeted CGM products; the work described in this workshop report builds on progress made through previous workshops.
Intellectual Merit The CGM will provide input for a variety of SCEC research, for example investigations of transient deformation, distributed crustal strain, and postseismic signals. Building the CGM has required evaluation and refinement of existing methods as well as development of new approaches in order to rigorously incorporate the results of multiple analyses applied to two different data types.
Broader Impacts Students and postdoctoral scholars have been active participants in the CGM project, particularly in the development of new methodology. The CGM will provide input for studying a variety of deformation processes, including those related to crustal strain accumulation as pertaining to seismic hazard assessment and time varying deformation that may relate to periods of increased hazard. Furthermore, the CGM will record non-tectonic signals, enabling assessment, for example, of hydrologic processes that may relate to drought or anthropogenic effects on water resources. In these ways, the CGM supports a better understanding of phenomena that directly impact the general public.
Exemplary Figure Figure 1: Left – Comparison between GPS daily solutions provided by UNAVCO for station LGWD and InSAR time series derived using different software packages and algorithms for the location of LGWD. Cyan and magenta dots are GPS daily solutions in ITRF08 projected into satellite LOS directions. Blue and red curves, respectively, represent the descending and ascending solutions (Xu, 2017) using GMTSAR. Black and grey curves show the descending and ascending solutions by Zhen Liu using ISCE and framework developed by H. Fattahi. Green and yellow curves show descending solutions (Neely et al., 2017) using GMTSAR, with different degrees of smoothing applied. All curves are referenced to zero displacement at the start of time series. Right – LOS velocity map produced from descending track T71 with constraints from GPS ITRF08 velocity field (Xu, 2017). Location of GPS station LGWD marked by yellow square. Figure credit: Xiaohua Xu, Scripps Institution of Oceanography
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