Abstract: With the continuous development of global climate change, the widespread modern glaciers may further melt or even completely disappear, resulting in the temporal and spatial changes of surface deformation, stress, and fault seismic risk in Qilian Mountains. In this paper, a plane-strain viscoelastic finite element program was developed to calculate the spatial and temporal evolution of surface deformation and ground stress in Qilian Mountains during the 150-year period from 1956 to 2106 under the surface load caused by glacier melting and the continuous tectonic compression. We calculated the normal stress, shear stress, and the change of Coulomb stress on the main faults in Qilian Mountains. The changes of seismic risk on each fault were quantitatively estimated. The surface uplift rate of Qilian Mountains is controlled by the ice rebound. The surface uplift rapidly increase at the beginning and then tends to be stable under the continuous melting of Qilian Mountains glacier. The horizontal stress, vertical stress, and shear stress change obviously under the effects of glacier melting and boundary tectonic loading. The Coulomb stress changes ΔCFS of the DZF, HSF, and HNF continuously increase, and the seismic risk increases in the future. Coulomb stress changes on the YAF and QNF faults are very small, and the seismicity seismic risk changes little. The numerical simulation provides a theoretical reference for understanding the spatial and temporal variation of future earthquake risk in Qilian Mountains under the glacier melting and tectonic loading.

Key words: finite element model, visco-elasticity, seismic risk, Qilian Mountains, glacier