Complete Coulomb failure stress changes and stress triggering of Yunnan Longlingearthquake sequence

X. P. Wu (1) , H. Fu (2) , Michel Bouchon (3) , J. F. Hu (1) , Y. L. Hu (1) , Yue Huang (2) , X. L. Hu (2) , C. D. Xie (1)

1 Department of Geophysics of Yunnan University
2 Earthquake Administration of Yunnan Province
3 LGIT - Laboratoire de Géophysique Interne et Tectonophysique

The complete Coulomb failure stress changes caused by the 1976 Ms73, Ms74 Yunnan Longling double main earthquakes are calculated. And dynamic and static stress triggering effects on the after earthquake sequence are studied. The results show that the second main earthquake is subjected to the triggering effect of dynamic and static Coulomb stresses induced by the first main earthquake. Among the thirteen strong aftershocks of the double main earthquakes, 90% of the aftershocks occurred inside the triangle block are subjected to the triggering effect of dynamic and static Coulomb stresses induced by the first or the second main earthquakes. And 2/3 of the aftershocks occurred outside the triangle block are subjected to the triggering effect of dynamic and static Coulomb stresses induced by the second main earthquakes. The dynamic and static stresses triggering effects of the second main earthquake are stronger than the first main earthquake both in intensity and in extent. In near field the numbers of aftershocks triggered by dynamic and static Coulomb stress are about equal. However the range of triggering effect of dynamic Coulomb stress is larger than that of static Coulomb stress.

Keywords: Complete Coulomb failure stress changes; Dynamic and static stress triggering; Earthquakes in Yunnan

X. P. Wu, H. Fu, Michel Bouchon, J. F. Hu, Y. L. Hu, et al.. Complete Coulomb failure stress changes and stress triggering of Yunnan Longlingearthquake sequence. Chinese Journal of Geophysics, 2007, 50 (4), pp.1111 à 1122. ⟨insu-00348246⟩