NUMERICAL MODELLING OF EVOLUTION OF TECTONIC STRESS FIELD IN STRONG EARTHQUAKE AREA

This paper examines the tectonic stress field in the Longmenshan region where the Wenchuan 8.0 earthquake occurred in 2008.The evolution of tectonic stress field before-,during-and after-earthquake is studied with numerical modelling.It is found that from the time before main shock to the time after main shock,the regional stress field experienced complex change process.The magnitudes and orientations of principal stresses and shear stresses changed a great deal.The changes coincide well with the deformation caused by the earthquake and the distribution of the after-shocks.