Improved imaging of Southern California crustal deformation using InSAR and GPS

Zhen Liu, Paul Lundgren, & Zheng-Kang Shen

Published September 2014, SCEC Contribution #2038

Differential interferometric synthetic aperture radar (InSAR) provides the capability to image surface deformation of plate boundary zones at fine spatial resolution with coarse temporal sampling. More than 18 years of extensive SAR data collection over southern California makes it now possible to generate a long time interval InSAR-based LOS velocity map to examine the resolution of both steady-state and transient deformation processes. As of date, we have performed systematic InSAR time series analysis of crustal deformation in southern California using ~18 yrs ERS-1/2 and Envisat data from all ascending and descending tracks since 1992. For the Envisat data, our results show a new source of temporally correlated ramp drifting error across the range that can significantly affect the resultant time series and mean line-of-sight (LOS) velocity map. Such error source was recently discovered and attributed to long term local oscillator (LO) frequency drift of Envisat ASAR sensor [Marinkovic & Larsen, 2013]. Correction of such error source, along with other noise sources, proves important to generate accurate InSAR deformation map. We adopt an empirical approach to correct such noise and show that such correction achieves comparable result as the approach that base on a priori GPS model. The RMS misfit between corrected InSAR LOS velocity and CMM4 GPS velocity is less than a few mm/yr. We present the results of the improved analysis to all ascending Envisat tracks. We also revisit our previous observation of long-term transient across Eastern California Shear Zone by combining ERS-1&2 and corrected Envisat SAR data and show such transient are still present in broad spatial extent even after taking into account such time-dependent ramp drifting error.

Liu, Z., Lundgren, P., & Shen, Z. (2014, 9). Improved imaging of Southern California crustal deformation using InSAR and GPS. Poster Presentation at SCEC Annual Meeting 2014.