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. Citation: Wang, H., T. J. Wright, and J. Biggs (2009), Interseismic slip rate of the northwestern Xianshuihe fault from InSAR data, Geophys. Res. Lett., 36, L03302, doi: 10.1029/2008GL036560.