Time‐dependent land uplift and subsidence in the Santa Clara valley, California, from a large interferometric synthetic aperture radar data set

TLDR

The study uses seasonal versus long‑term uplift patterns to constrain the spatial and temporal characteristics of aquifer water‑bearing units. The authors inverted 115 differential interferograms from 47 SAR scenes using linear and nonlinear range‑change models to derive a time‑dependent deformation signal across the valley. Cumulative uplift of up to 41 mm occurred 1992–2000 north of Sunnyvale, with additional uplift east of San Jose and seasonal uplift/subsidence of ~35 mm west of the Silver Creek fault, which acts as a hydrologic barrier and indicates fault activity since Quaternary deposition.

Abstract

We invert 115 differential interferograms derived from 47 synthetic aperture radar (SAR) scenes for a time‐dependent deformation signal in the Santa Clara valley, California. The time‐dependent deformation is calculated by performing a linear inversion that solves for the incremental range change between SAR scene acquisitions. A nonlinear range change signal is extracted from the ERS InSAR data without imposing a model of the expected deformation. In the Santa Clara valley, cumulative land uplift is observed during the period from 1992 to 2000 with a maximum uplift of 41 ± 18 mm centered north of Sunnyvale. Uplift is also observed east of San Jose. Seasonal uplift and subsidence dominate west of the Silver Creek fault near San Jose with a maximum peak‐to‐trough amplitude of ∼35 mm. The pattern of seasonal versus long‐term uplift provides constraints on the spatial and temporal characteristics of water‐bearing units within the aquifer. The Silver Creek fault partitions the uplift behavior of the basin, suggesting that it acts as a hydrologic barrier to groundwater flow. While no tectonic creep is observed along the fault, the development of a low‐permeability barrier that bisects the alluvium suggests that the fault has been active since the deposition of Quaternary units.