Seismic Hazard Quantitative Evaluation Of Longmen Shan And Surrounding Area After Wenchuan Earthquake

China is a country prone to earthquakes, as of now, earthquake prediction is still aworldwide scientific problem. In nowadays, long-term seismic hazard assessment becomesmore and more important. Stress conditions of active faults in the Longmen Shan andsurrounding areas changed significantly after Wenchuan earthquake. Therefore, it isimportant to quantitative estimate the earthquake hazard of the Longmen Shan andsurrounding areas. Nevertheless, there are still some fundamental problems which shouldbe figured out. One is fault activity analysis, and the other is Coulomb stress calculation.Besides, the seismic hazard quantitative assessment also should be investigated. Faultactivity analysis identifies the main risk areas; Coulomb stress calculation estimate stressperturbation on active faults caused by the great Wenchuan earthquake; At last, we estimatethe earthquake occurrence probability on active faults.Based on GPS velocity field data, we calculated the difference between the motion ofmain blocks. Using these results as constraint, we calculated the slip rate and locking depthof main active faults with rngchn program based on Okada model. The result shows that:the locking depths were more than20Km on Daofu-Kangding section of Xianshuihefault, Anninghe fault and Zemuhe fault. It is higher than other active faults in Sichuan andYunnan region. Therefore, seismic risks are higher, too.With the focal mechanism of Wenchuan earthquake and the fine rupture model whichbased on near-field displacement field, we analyzed the changes of regional tectonic stressfield, and estimated earthquake occurrence probability on neigh-borhood faults. After that,we simulated the postseismic viscoelastic Coulomb stress evolution on Lushan earthquakefocus region and the surrounding faults with earth stratified medium model. The resultshows that the Luhuo-Luding section of Xianshuihe fault has obvious stress increase, themost significant change of Coulomb stress is0.67bar. Wenchuan earthquakecoseismic Coulomb stress change is not obvious on Lushan earthquake focus region.However, viscoelastic Coulomb stress change played an important role in the promoting ofLushan earthquake.This thesis explores the method for seismic hazard quantitative evaluation of activefaults based on GPS. Using GPS velocity field before the2008Wenchuanearthquake, combined with a variety of earthquake probability models, we obtained thebackground seismicity and earthquake probability of main active faults in researcharea. With the consideration of Wenchuan earthquake stress disturbance, we finally got theearthquake probability of main faults after Wenchuan earthquake.