The Evolution of Stress and Strain around the Bayan Har Block in the Tibetan Plateau

Abstract

With the constraint of GPS observation, the tectonic deformation of the Bayan Har block and its periphery faults is investigated based on an elastoplastic plane-stress finite element model. The results show that the elastic model cannot explain the current GPS observation in the Bayan Har block. When East Kunlun fault and Yushu-Xianshuihe fault are under plastic yield state or high strain localization, the calculated velocities fit well with the observation values. It indicates that most of the current shear deformations or strain localizations are absorbed by these two large strike-slip faults. In addition, if the recurrence intervals of large earthquakes are used to limit the relative yield strength of major faults, the order of entering the plastic yield state of the major faults around Bayan Har block is as follows. The first faults to enter the yield state are Yushu-Xianshuihe faults and the middle segment of East Kunlun faults. Then, Margaichaka-RolaKangri faults (Mani segment) and Heishibeihu faults would enter the yield state. The last faults to enter the yield state are the eastern segment of East Kunlun faults and Longmenshan faults, respectively. These results help us to understand the slip properties of faults around the southeastward moving Bayan Har block.