Effects of fault movement and material properties on deformation and stress fields of Tibetan Plateau

Abstract

We compare the factors which affect the movement of Tibetan Plateau by building three types of finite element models: an elastic materials (M-EC), a continuous model composed by non-linear materials (M-PC), and an elastic model with discontinuous fault movements (M-ET). Both in M-ET and M-EC, the materials in Qiangtang and Lhasa block are elastic, and in M-ET, discontinuous movement of faults is considered for evaluating the effects of strike-slip faults. In model M-PC Druker-Prager plastic materials are used in Qiangtang and Lhasa block. Comparisons of the numerical simulation and the GPS observations show following characteristics: (1) Under present tectonic environment, short-term deformation of Tibetan Plateau can be simulated well by elastic models; (2) Discontinuous fault activities increase the lateral extrusion of the eastern part of Tibetan Plateau, reduce the stress field level in Qiangtang, Tarim and Qaidam blocks and strengthen the E-W extensional force in the east and the west parts of Qiangtang block; (3) Properties of plastic materials reduce the total stress field and the E-W extensional force, thus, the normal fault earthquakes in southern Tibet is mainly owed to the effect of active fault movement. Based on the numerical simulations we speculate that faults movement may play a more important role on the kinematic pattern of Tibetan Plateau than bulk properties.