Resolving vertical tectonics in the San Francisco Bay Area from permanent scatterer InSAR and GPS analysis

Abstract

Using a combination of GPS-measured horizontal velocities of 200 sites and 115,487 range-change rates determined with the permanent scatterer interferometric synthetic ap- erture radar (InSAR) method in the San Francisco Bay Area, we resolve vertical motions in the region at sub-mm/yr precision. The highest displacement rates are due to nontec- tonic processes, such as active landslides, subsidence and rebound over aquifers, and rapid settling of unconsolidated sediments along the bay margins. Residual displacement rates are determined by removing the contribution of the GPS-derived horizontal velocity field from the InSAR range-change rates. To isolate vertical tectonic rates, we use only those InSAR measurements made on material that was not Quaternary substrate, which is sus- ceptible to nontectonic and seasonally varying ground motions. The InSAR residuals in- dicate significant uplift over the southern foothills of the active Mount Diablo anticlinor- ium, the Mission Hills stepover region of the Hayward and Calaveras faults, and the central and southern Santa Cruz Mountains located along a restraining bend of the San Andreas fault.