Interseismic slip rate of the northwestern Xianshuihe fault from InSAR data

The Xianshuihe fault is a highly active strike‐slip fault system near the eastern margin of the Tibetan plateau. We use a multi‐interferogram method to construct a map of line‐of‐sight deformation rate due to interseismic strain accumulation on the northwestern Xianshuihe fault from a decade of SAR data acquired by the ERS‐1/2 and Envisat satellites. The rate map shows a clear deformation gradient associated with the fault, but slightly offset to the northeast from the surface trace. Joint inversion of InSAR rate map and GPS data using Monte‐Carlo method, we estimate a slip rate of 9‐12 mm/yr with a locking depth of 3‐6 km at the 90% confidence level. The slip rate agrees with the Holocene fault slip rate and the historical earthquakes. Our results also suggest no significant across‐fault extension. In the future, InSAR data from both ascending and descending orbits may further constrain the 3‐D fault slip rate on this fault.