Tectonic and Anthropogenic Deformation Surrounding the Cerro Prieto Geothermal Field from Sentinel-1 Interferometry

Xiaohua Xu

Submitted August 8, 2016, SCEC Contribution #6553, 2016 SCEC Annual Meeting Poster #168

The Cerro Prieto Geothermal Field (CPFG) lies at the step-over between the Imperial and Cerrro Prieto Faults in northern Baja California. While this is the most tectonically active section of the San Andreas Fault system, the spatial and temporal deformation in the area is poorly resolved by the sparse GPS coverage. Moreover interferograms spanning more than a few months are decorrelated due to the extensive agricultural activity in the region. Here we investigate the use of frequent, short temporal baseline interferograms offered by the new Sentinel-1 satellite to recover two components of deformation time series across these faults. The Sentinel-1 satellite uses a new wide-swath mode called Terrain Observation with Progressive Scans (TOPS) to acquire complete spatial coverage on a 12-day or 24-day cadence from two look directions [Meta et al., 2010]. While this new technique enables frequent acquisitions, it brings new challenges to InSAR data processing in alignment and co-registration [Prats-Iraola et al., 2012]. Following other groups, we have developed a purely geometric approach to image alignment that achieves better than 1/200 pixel alignment needed for accurate phase recovery. One significant advantage of pure geometric alignment is that phase correlation between SAR images is not needed. Therefore long time span deformation can be accurately constructed from a sum over short time span interferograms because atmospheric and orbital errors of the intervening SAR images cancel. In practice we construct InSAR time series using a coherence-based SBAS method [Tong and Schmidt, 2016] with atmospheric corrections by means of common-point stacking [Tymofyeyeva and Fialko 2015]. Preliminary results, clearly resolve the spatial and temporal subsidence at CPGF. The maximum subsidence rate of 150 mm/yr, due to extraction of geothermal fluids and heat, dominates the expected 40 mm/yr deformation across the proximal ends of the Imperial and Cerro Prieto Faults. We combine a two-year time series of ascending (34) and descending (42) Sentinel-1 images to map the details of the fault-parallel deformation away from the CPFG.

Key Words
InSAR, Time Series, Deformation

Citation
Xu, X. (2016, 08). Tectonic and Anthropogenic Deformation Surrounding the Cerro Prieto Geothermal Field from Sentinel-1 Interferometry. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Tectonic Geodesy