SCEC Award Number 13054 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Developing InSAR deformation map towards improved Community Geodetic Model
Investigator(s)
Name Organization
Zhen Liu University of California, Los Angeles
Other Participants Zheng-Kang Shen (UCLA), 1 Graduate Student
SCEC Priorities 1, 5, 2 SCEC Groups Geodesy
Report Due Date 03/15/2014 Date Report Submitted N/A
Project Abstract
 Towards an improved time-dependent Community Geodetic Model (CGM) constrained by both GPS and InSAR data, we are developing InSAR time series and deformation map for the entire southern California through systematic processing and analyzing large volume of SAR data from both ascending and descending tracks of C-band ERS-1, 2 and Envisat satellites. The consistent orbital geometries and scenes from three satellites and temporal overlapping between ERS-2 and Envisat allow us to combine them to generate > 18 years InSAR time series since 1992. To maximize independent information from InSAR, we minimize usage of GPS based constraint in the analysis. The derived InSAR-only deformation map and time series provide the baseline products for further comparison and improvement. As of the date, we have completed preliminary InSAR processing and time series analysis for all descending and ascending tracks (16 tracks in total). We presented our results in 2013 SCEC CGM workshop in Menlo Park and 2013 SCEC Annual Meeting [Liu et al., 2013]. We also participated and contributed our result to CGM group effort CosInED (Comparative study of InSAR estimates of deformation) exercise. The derived InSAR deformation and time series show the complex pattern of surface deformation signals related to steady strain accumulation due to fault locking, fault creeping, time-varying transient, and anthropogenic induced uplift and ground subsidence. The 18-years combined time series also show clear long term transient across the East California Shear Zone, and broad postseismic deformation signals following the 1996 Hector Mine earthquake.
Intellectual Merit The project directly contributes to the development of a Community Geodetic Model (CGM) by deriving InSAR deformation map as an immediate step towards CGM. The results can improve our understanding of the processes underlying transient deformation signals and/or their seismic hazard implications by highlighting areas and/or GPS sites that are subject to non-steady time-varying tectonic/nontectonic deformation processes and providing better observational constraints on their physical mechanism. It also contributes to the stress and deformation over time (SDOT) by providing better constrained present-day state of deformation on crustal-scale faults in southern California for the development of community stress model, models of interseismic and earthquake cycle deformation as well as 4-D geodynamic models for improved seismic hazard analysis.
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 also enhances the infrastructure, research and education partnership between JIRESSE and Department of Earth & Space Sciences at UCLA by involving graduates into research as part of their summer activities.
Exemplary Figure Figure 1. Mosaic view of the mean LOS velocity map from the decending tracks 170, 399, 127, 356, and 84 using ERS-1/2 and Envisat data in 1992-2010. The velocity map is rewrapped at 2 cm/yr. Note that certain tracks are displayed with ERS derived LOS map only to separate the large postseismic deformation signals of the Hector Mine earthquake. Right panel shows LOS velocity in the black box region on the left at two different time periods (1992-2002, 2002-2010) and differential LOS time series between b(t) and B(t), indicating long term transient across this part of ECSZ.