Imaging tectonic and anthropogenic processes using ALOS-2 and Sentinel-1 InSAR

Zhen Liu, Paul Lundgren, & Cunren Liang

Published August 16, 2019, SCEC Contribution #9905, 2019 SCEC Annual Meeting Poster #210

The improved spatiotemporal resolution of surface deformation from recent satellite sensors such as Sentinel-1 (S-1) and ALOS-2 provides a great opportunity to better constrain and understand both tectonic and non-tectonic processes. In this study, we combine satellite InSAR and in-situ GPS to image fault and anthropogenic deformation. We present InSAR time series results in central and southern California region from selected tracks using S-1 and ALOS-2 ScanSAR data. We estimate azimuth mis-registration between single look complex (SLC) images of S-1 in a stack sense to achieve accurate azimuth co-registration between SLC images for low coherence and/or long interval interferometric pairs. The pervasive existence of ionosphere artifacts in ALOS-2 ScanSAR interferometry makes it crucial to properly correct them for accurate deformation measurements. We show a split-spectrum based ionosphere correction is able to remove ionospheric features successfully while still retaining long-wavelength deformation signals. Our results in central California reveal the large-scale ground subsidence in the San Joaquin Valley due to over-exploitation of groundwater along with localized near-fault creep across the central San Andreas Fault. Groundwater related deformation is spatially and temporally variable and is composed of both recoverable elastic and non-recoverable inelastic components. InSAR time series are compared to GPS and well-water hydraulic head in-situ time series to understand water storage processes and mass loading changes. Our ALOS-2 ScanSAR velocities across the southern San Andreas fault system show that they agree well with GPS velocities, with an RMS error ~4-5mm/yr. The consistency between ALOS-2 and GPS over large areas suggests that ALOS-2 ScanSAR data have great potential in mapping long-wavelength deformation signals accurately without reliance on using GPS as ground control points.

Citation
Liu, Z., Lundgren, P., & Liang, C. (2019, 08). Imaging tectonic and anthropogenic processes using ALOS-2 and Sentinel-1 InSAR. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy