Measurement of fault creep using multi-aspect terrestrial radar interferometry at coyote dam

The Calaveras fault passes directly through Coyote Dam located near Gilroy, California. The earthen structure of the dam was constructed to withstand the expected deformation due to fault creep at a rate of 10 to 15 mm/year. As part of a possible dam retrofit, the Santa Clara Valley Water District initiated a series of measurements using a Ku-Band terrestrial interferometer to accurately localize the fault trace through the dam. Measurements over the period 12-May 2016 to 18-Nov-2016 were acquired from 4 different positions situated around the down-stream face. Time series of measurements from each position were obtained after performing corrections for variable tropospheric phase delay. These measurements were combined using least-squares estimation to generate three-dimensional maps delineating both stable and rapidly deforming regions.