Deformation characteristics of the 2016 Mw5.9 Menyuan (China) earthquake by modelling Sentinel-1A and auxiliary data

Abstract

ABSTRACTThe 2016 Mw5.9 Menyuan earthquake occurred on the Qilian-Haiyuan fault system on the northeastern margin of the Tibetan Plateau. Since the seismogenic source is a blind fault, it is difficult to obtain reliable geometric parameters of the source only from the satellite data. In this paper, we used two aftershock relocation data sets to constrain the seismogenic fault, and obtained two southwest-dipping listric fault models with a strike of about 126° and different dip angles. According to the geological structures, we assumed that the dip is uniformly reduced along the width direction, and modelled the Interferometric Synthetic Aperture Radar (InSAR) data of the Menyuan event using a simulated annealing algorithm to search for the optimal fault dips. The optimal top and bottom dips are about 59° and 1°, respectively. Using the optimal fault model, we obtained the slip distribution and three-dimensional displacement fields for the 2016 Mw5.9 Menyuan earthquake. Sliding occurs mainly on the four sub-faults in the middle of the model, indicating that the rupture zone is relatively small. The displacement fields indicate that the seismogenic source is a thrust fault, and the epicentre experienced a strong northeastward compression deformation.