Characterizing interseismic deformation of the Xianshuihe fault, eastern Tibetan Plateau, using Sentinel-1 SAR images

Abstract

The Xianshuihe fault is a very large left-lateral strike-slip fault, located on the eastern boundary of the Tibetan Plateau. In the late Cenozoic, this fault played a vital role in accommodating crustal deformation of the eastern Tibetan Plateau. High-spatial-resolution deformation measurements are key to understanding the deformation mechanism (block-like mode or continued mode) and seismic potential of this fault. However, due to the high elevation, harsh field conditions, and dense vegetation coverage, such data has not been available until now. In this study, we processed two descending tracks of Sentinel-1 images taken between 2015 and 2018 to obtain high-spatial-resolution deformation velocity fields of the Xianshuihe fault. Fault slip rate distribution was then inverted using interferometric synthetic aperture radar (InSAR)-derived deformation as a constraint. Moreover, the seismic potential was evaluated by combining the interseismic fault movement, rupture of major historical earthquakes, and modern seismicity distribution. The results are as follows. (1) The present-day slip rate of the Xianshuihe fault is constrained as 9–12 mm/yr, and along-strike variations of the slip rate are small, in contrast to geological results but similar to GPS results. (2) The crustal material properties constrained by InSAR/GPS differ on either side of the Xianshuihe fault, in agreement with seismological data. (3) Shallow creep is occurring along the northwest Xianshuihe fault. (4) Local near-field post-seismic deformation is likely related to the 2014 Kangding M6.3 earthquake sequence. (5) The Qiajiao, Daofu, and Bamei segments are capable of strong earthquakes.