Modeling dynamics of block-and-fault systems and seismicity

A model of block-and-fault system dynamics (a block model) has been developed to analyze how the basic features of seismicity depend on the lithosphere structure in a region under consideration and peculiarities of its dynamics. The lithosphere in the region is modeled by a system of perfectly rigid blocks divided by infinitely thin fault planes. The viscoelastic interaction between blocks themselves and with the underlying medium is specified. Displacements and rotations of blocks at each time moment are determined so that the whole block system would be in a quasistatic equilibrium state. When the ratio of the stress to the pressure exceeds the critical level in some part of a fault zone, a stress drop occurs that is considered in the model as an earthquake. The paper contains a review of results obtained by numerical simulation of different block structures dynamics including the structures approximating the lithosphere structure in specific active regions. These results give a hope that the block model is a useful tool for studying relations between geometry and movements of faults and blocks and seismicity features.