In this paper, according to Coulomb fracture criterion, the discrete wave number method is used to calculate the dynamic Coulomb stress variation of the 1999 Chi-Chi MS7.6 earthquake in Taiwan on Fuzhou ML3.8 earthquake. The results show that the stress change value exceeds the trigger threshold at 105.1,114.51,116.08 and 127.84 seconds after the earthquake, and the maximum value is about 0.74 MPa at 116.08 seconds, which shows that the Chi-Chi MS7.6 earthquake in Taiwan can trigger the Fuzhou ML 3.8 earthquake by dynamic stress. In addition, according to the dynamic Coulomb fracture stress field propagation diagram at different times after the 7.6 earthquake,it can be seen that the occurrence of the largest aftershock may be jointly triggered by the dynamic and static triggering of the Chi-Chi earthquake.
图2 台湾集集7.6级地震震后距离福州ML3.8地震震中最近网格点处的动态库仑破裂应力变化值图Fig. 2 The dynamic Coulomb fracture stress variation at the nearest grid point to the epicenter of the Fuzhou ML3.8 earthquake after the Chi-Chi M7.6 earthquake in Taiwan