摘要
This paper approaches the neotectonic stress field based on the data of foeal mechanismsolution,ground stress measurement,tectonic mechanical analysis and geodetic surveying,and finds out that the orientations of the maximum principal comproessive sterss patterns arequite discordant with different methods and the stress patterns are widely differnt betweenthose in the shallow and deep part of the crust in North China.Based on the analysis ofabove-mentioned data,we established a duplex model by considering the diversities of theStress patterns in 3-dimentional spaces,the boundary conditions and the lithospheric media,and made an inverse calculation by using the finite element method.The calculated results fitwell with the reality in North China,i.e.the stress patterns in lower crust which is below thedetachment interface at the deptp of 10 km from ground surface are relatively consistent withnearly horizontal state and NE-ENE trending of the maximum principal compressive stressaxes,whereas the stress
This paper approaches the neotectonic stress field based on the data of focal mechanism solution, ground stress measurement, tectonic mechanical analysis and geodetic surveying, and finds out that the orientations of the maximum principal compressive stress patterns are quite discordant with different methods and the stress patterns are widely different between those in the shallow and deep part of the crust in North China. Based on the analysis of above-mentioned data, we established a duplex model by considering the diversities of the stress patterns in 3-dimentional spaces, the boundary conditions and the lithospheric media, and made an inverse calculation by using the finite element method. The calculated results fit well with the reality in North China, i.e. the stress patterns in lower crust which is below the detachment interface at the depth of 10 km from ground surface are relatively consistent with nearly horizontal state and NE-ENE trending of the maximum principal compressive stress axes, whereas the stress patterns in upper crust which is above the detachment interface are widely divergent with extensional state in polydirections. Therefore, small earthquakes are prone to occur in the shallow part while large earthquakes are generated in the lower crust. The hypocentral location for a potential large earthquake may be inferred from the shearing stress distribution calculated by finite element method based on the duplex model.
