On May 12,2008,a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province,China,collapsing buildings and killing tens of thousands people.As predicted,aftershocks may last for at least one year,and moreover,large aftershocks are likely to occur.Therefore,it is critical to outline the areas with potential aftershocks before reconstruction and resettling people as to avoid future disasters.It is demonstrated that the redistribution of stress induced by an earthquake should trigger successive seismic activity.Based on static stress triggering theory,we calculated the coseismic stress changes on major faults induced by the Wenchuan earthquake,with elastic dislocation the-ory and the multilayered crustal model.We also discuss the stress distribution and its significance for future seismic activity under the impact of the Wenchuan earthquake.It is shown that coulomb failure stress(CFS) increases obviously on the Daofu-Kangding segment of the Xianshuihe Fault,the Maqu and Nanping segment of the Eastern Kunlun Fault,the Qingchuan Fault,southern segment of the Min-jiang Fault,Pengxian-Guanxian Fault,Jiangyou-Guangyuan Fault,and Jiangyou-Guanxian Fault.The increased stress raises the probability of earthquake occurrence on these faults.Since these areas are highly populated,earthquake monitoring and early disaster alarm system are needed.CFS increases with a magnitude of 0.03―0.06 MPa on the Qingchuan Fault,which is close to the northern end of the rapture of Wenchuan earthquake.The occurrence of some strong aftershocks,including three events with magnitude higher than 5.0,indicates that the seismic activities have been triggered by the main shock.Aftershocks seem to migrate northwards.Since the CFS change on the Lueyang-Mianxian Fault located on the NEE of the Qingchuan Fault is rather small(±0.01 MPa),the migration of aftershocks might be terminated in the area near Hanzhong City.The CFS change on the western Qinling Fault is around 10 Pa,and the impact of static triggering can be neglected.T
