SCEC Award Number 16275 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Improve and combine InSAR deformation map and GPS for Community Geodetic Model
Investigator(s)
Name Organization
Zhen Liu University of California, Los Angeles
Other Participants Zheng-Kang Shen (UCLA);
Graduate Student (1, TBD)
SCEC Priorities 1d, 1e, 5b SCEC Groups Geodesy
Report Due Date 03/15/2017 Date Report Submitted 03/14/2017
Project Abstract
 We have processed and analyzed a large volume of C-band ERS-1&2 and Envisat SAR data to produce the InSAR time series and deformation map in the southern California. Detailed comparison between InSAR-only deformation map and GPS shows that there is no systematic residual ramp discrepancy. We find that the descending tracks, which typically have more acquisitions and long-duration, are in better agreement with GPS (RMS error ~1-3mm/yr) than ascending tracks. The ascending tracks, which have mainly Envisat data and fewer dates, tend to have larger RMS errors (~3-6 mm/yr) as compared to GPS, possibly related to larger residual atmosphere noise caused by limited number of SAR scenes and inadequate noise reduction. We develop a new approach for a combined 3-D deformation field from a joint analysis of InSAR and GPS data and more rigorous ways to account for the uncertainties of interpolated GPS velocity field and uncertainties associated with InSAR deformation map. We have applied the new approach to selected tracks and show that combining InSAR and GPS clearly improves the resolution of small-scale deformation signals especially in the vertical direction. We collaborated with researchers in the SCEC community to combine InSAR velocities with GPS to constrain the kinematics of metropolitan Los Angeles faults in a slip-partitioning model using a Bayesian approach. We presented our results and shared our findings at SCEC workshops and annual meetings. Our results were also mentioned as part of the SCEC4 Science accomplishments and included in the SCEC5 proposal.
Intellectual Merit The project contributes to producing a consensus secular velocity field through improved InSAR deformation map and error characterization. The unified well-constrained 3-D deformation map especially vertical components will provide crucial constraint to the development of physically more realistic deformation models and other SCEC community models (e.g., CRM and CSM). Developing robust methods for GPS/InSAR integration will contribute to the development of 4-D system-wide integrated deformation model. It also contribute to developing and providing better constrained present-day state of deformation on crustal-scale faults thus contribute to the development of system-wide deformation models for physics-based probabilistic seismic hazard analysis for southern California, and developing models of interseismic, earthquake cycle and long-term deformation.
Broader Impacts The research activity promotes the solid earth component of crustal deformation and earthquake dynamics studies within the Joint Institute for Regional Earth Systems Science & Engineering (JIRESSE) where traditional focuses have been on ocean and atmosphere science. It enhances the infrastructure, research and education partnership between JIRESSE and Department of Earth & Space Sciences at UCLA.
Exemplary Figure Figure 1,4