Numerical Simulation on Magnitude 7 or over Earthquakes in Southeast Gansu Province and Its Neighboring Areas

Yang Xingyue; Zeng Wenhao; Wang Yan; Li Shaohua; Sun Zhaohua

doi:10.3799/dqkx.2016.102

Abstract：It is very important to study the influence of the strong earthquake on the surrounding fault and its development trend in future.Strong earthquakes occurred frequently in the northeastern margin of the Qinghai-Tibet Plateau,thus it is necessary to study the history of strong earthquakes in this region.We construct the 3D viscoelastic finite element model of the northwest margin and its surroundings of Qinghai-Tibet Plateau,on the basis of level Ⅰblocks in China continent and level Ⅱ blocks in Qinghai-Tibetan Plateau and distribution of active faults to determine the model block boundary and fault location in this paper. In addition,the dynamic process of strong earthquakes (M s ≥ 7.0 )since 1 900 is simulated using GPS observation data as boundary conditions,The calculation results are as follows.(1 )The regional horizontal tectonic stress field in northeastern margin of Tibetan Plateau is characterized by gradual decrease from west to east and decrease from south to north as well.(2) The simulation results show that the strong earthquakes are mainly caused by the equivalent stress loaded on the background field and the strong earthquakes.(3)The effects of historical earthquake sequence to the earthquakes since 1 970 are also dis-cussed.It is concluded that the Kangding earthquake triggered the occurrence of Luhuo earthquake acceleratedly,while the effect of Kangding earthquake,Luhuo earthquake and Songpan earthquake on Gonghe earthquake is not obvious,meanwhile, the influence of Luhuo earthquake,Songpan earthquake and Gonghe earthquake on the Wenchuan earthquake is little;and the Wenchuan earthquake delayed the occurrence of Lushan earthquake.