Sentinel-1 InSAR observations of co- and post-seismic deformation mechanisms of the 2016 Mw 5.9 Menyuan Earthquake, Northwestern China

Abstract

On January 21, 2016, a Mw 5.9 earthquake occurred in Menyuan, Qinghai Province, in northwestern China, which is an earthquake-prone region located along the northeastern margin of the Tibetan Plateau. However, the source parameters, deformation mechanism, especially the influence of this earthquake on the surrounding regions and on post-seismic deformation, remains poorly understood. In this study, Sentinel-1 images from ascending and descending tracks were used to investigate the co- and post-seismic deformation fields. Uniform and distributed slip models were used to determine the source parameters. Finally, the co- and post-earthquake two-dimensional (2D) deformation decomposition, coulomb failure stress changes caused by the 2016 Menyuan earthquake, and the influence of this event on the surrounding region and active faults were analyzed. The results suggest that the 2016 Menyuan earthquake was triggered by a concomitant buried reverse fault in the northeastern part of the Northern Lenglongling Fault, which is a SW dipping sinistral thrust fault with a strike angle of 140°. The fault properties are consistent with the results of Interferometric Synthetic Aperture Radar (InSAR) 2D decompositions. The co-seismic deformation of the two satellite tracks have maximum line-of-sight uplifts of 55 mm and 65 mm, without notable subsidence. The post-seismic effect of the earthquake mainly affected the area between the Lenglongling Fault and the Northern Lenglongling Fault. The earthquake caused stress loading on the southwest of the western segment of the Lenglongling Fault and on the southeast of the eastern segment of the Northern Lenglongling Fault, as well as along these two faults.