SCEC Award Number 14163 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Improving GPS Crustal Motion Map for Integrated Community Geodetic Model
Investigator(s)
Name Organization
Zheng-Kang Shen University of California, Los Angeles Yuehua Zeng United States Geological Survey
Other Participants Min Wang
SCEC Priorities 1a, 1d, 1e SCEC Groups Geodesy, WGCEP, SDOT
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
 We worked on processing/reprocessing all of the campaign GPS data collected in southern California 1986-2014. We have: (a) Searched UNAVCO and SCEC geodetic data archives and downloaded all the southern California campaign GPS data not incorporated into our previous solutions yet. (b) Solicited and obtained campaign GPS data from various research groups which had not been archived at the UNAVCO or SCEC data archives. (c) Inspected the new campaign GPS data and fixed problems with the metadata and coordinate information. (e) Selected sites for further analysis. (f) Selected the regional fiducials for campaign data processing. (h) Carried out daily processing/reprocessing of the campaign GPS data 1986-2002, and some of the new data 2004-2014. (i) Selected North America tracking sites and started reprocessing them 1994-2014 to tie the regional campaign network to a North America reference frame.
We also developed a method to optimally estimate strain field as a continuous function using discrete measurements. We apply this method to GPS velocity field in southern California, and find: (1) 2~3×10-7 strain/yr shear strain rates across the SAF from the Carrizo Plain to Coachella segment, the San Jacinto and Oak Ridge faults, and the Mojave Shear Zone; (2) North-south convergence of up to 1.5×10-7 strain/yr within the Los Angeles and Ventura basins; and (3) Orientations of dextral maximum shear strain rates coinciding well with strike directions of all sections of SAF, including the “Big Bend” region, suggesting that tectonic deformation field in southern California is dominated by mechanic processes of the SAF.
Intellectual Merit This research helps quantify fault slip rates at geodetic time scale.
The strain rate model helps differentiate ductile and elastic deformation associated with faulting process.
This research helps advance the CGM project by contributing the campaign GPS velocity and time series products. It strengthens collaboration with the UNAVCO community by incorporating campaign GPS data collected by the community into the joint solution.
The product of this research will be used for reassessment of postseismic and transient deformation without traditional simplifying assumptions.
Broader Impacts A postdoctoral scholar has been trained at UCLA.
The project promoted collaboration among SCEC scientists through telecommunications and discussions at the SCEC workshops and annual meeting.
Product of the project has the potential for advancing our knowledge on seismic hazard potentials.
Exemplary Figure Figure 3. Strain rate interpolation result using Gaussian/Voronoi cell weighting functions. The background color shows the second invariant of strain rates and the arrow pairs are the principal strain rates.
Credit: Shen, Z.-K., M. Wang, Y. Zeng, and F. Wang, Optimal Interpolation of Spatially discretized Geodetic Data, Bull. Seismol. Soc. Am., submitted, SCEC Publication #2077, 2015.
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.