NUMERICAL MODELING OF THE STRESSED STATE OF THE EARTH’S CRUST AND CONDITIONS OF DYNAMIC INSTABILITY OF SEISMOACTIVE FAULTS DURING RIFTING Available to Purchase

To receive insight into conditions of origin and preparation of earthquakes, the stressed state of the Earth’s crust and its variations have been investigated. With this aim, a detailed two-dimensional elastic model for a vertical section of the Earth’s crust has been developed. A model prototype is the central part of the Baikal Rift Zone. The model takes into account the distribution of elastic properties and density in the Earth’s crust, determined from data of seismic soundings, and includes a number of tectonic disturbances: the central depth fault and a number of peripheral faults including a listric one. The boundary conditions were specified on the basis of a complex of geologo-geophysical data, first of all, on mechanisms of earthquake foci and their spatial distribution. The conditions adopted chiefly correspond to a model for passive rifting. Numerical modeling of a stressed state by the method of finite elements has revealed potentially seismic places of anomalous concentrations of stresses. Modeling of the effect of external and internal additional factors (stress variations on the regional level, rigidity variations at the contact with fault sides) has revealed the most sensitive zones with a quantitative estimation of the effect of increased stresses in them.