Effect of Earth Models on Coulomb Stress Change Caused by Surface Load

摘要

Based on the elastic spherical Earth models, this study presents the radial Love numbers and Green's functions of the surface load problem, then evaluates the effect of different Earth models on the Coulomb stress changes due to elastic deformation by surface load. First of all, the radial load Love numbers are introduced and verified by comparing them with the results of an analytical method. Second, the formulae of the radial Green's functions of the internal displacements and strain tensors are obtained by summing the Love numbers. The results are compared with Green's function of half-space to verify the correctness. Then, the stress tensors are obtained by the constitutive relation. Finally, the Coulomb stress changes due to elastic deformation around the Wenchuan Mw7.9 earthquake by the impoundment load of the Zipingpu reservoir are calculated based on five Earth models. The results show that the elastic deformations caused by the impoundment load do not increase the seismicity rate in the study area. At the epicenter of the great event, the maximum effect due to the Earth models is about 38%. The stratification of the Earth is the main effect factor on the Coulomb stress change, and it should not be ignored in actual studies. The biggest difference of Coulomb stress changes based on the different stratified Earth models is close to 15%, which also cannot be ignored.