Applicability of Sentinel-1 Terrain Observation by Progressive Scans multitemporal interferometry for monitoring slow ground motions in the San Francisco Bay Area

Data from the Sentinel-1 satellite have already proven useful for investigating seismic and volcanic events since its launch in April 2014. The requirement of ultrahigh coregistration accuracy and the current relatively short time of Sentinel-1 acquisitions make its application challenging for studying slow deformation processes, such as fault creep and land subsidence. Here we analyze a set of 14 SAR images over the San Francisco Bay Area spanning 1 year from early 2015 to 2016. We show that implementing an existing Enhanced Spectral Diversity algorithm or using precise orbits together with a reference digital elevation model both yield the required coregistration accuracy for making use of the phase measurements in time series analysis of ground deformation. Following a thorough validation test, we update our estimates of Hayward Fault creep rate and confirm uplift due to recharge of the Santa Clara Valley aquifer system during the final summer of 4 year drought.