Partial coupling and earthquake potential along the Xianshuihe Fault, China

Abstract:

The left-lateral Xianshuihe Fault is located at the eastern boundary of the Tibetan Plateau and is one of the most active faults in China. It is associated with substantial seismic potential, with more than 20 Mw>6 earthquakes since 1700. The fault has been documented to be creeping at the surface for decades; however, the spatial and temporal distributions of shallow creep along the fault are not well resolved. In this study, we obtain high-resolution interseismic velocity maps along the 350-km-long central Xianshuihe Fault segment and timeseries along the Kangding region using ascending and descending Sentinel-1 data. Multiple creeping sections are identified and the estimated surface creep rates show high along-strike variability. A coupling model is derived to better characterize the distribution of creep with depth. The seismic potential of apparent rupture asperities along the Xianshuihe Fault can be further refined by considering fault-crossing baseline data, historical ruptures and microseismicity. Moreover, a stress-driven afterslip model around the Mw 5.9 2014 Kangding rupture reveals substantial shallow afterslip, which provides further constraints on the distribution of locked and creeping patches along this section of the Xianshuihe fault.