Numerical modeling of block structure dynamics: dependence of a synthetic earthquake flow on the structure separateness and boundary movements

Abstract

A seismically active region is modelled as a system of absolutely rigid blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is viscous-elastic. The system of blocks moves as a consequence of prescribed motion of the boundary blocks and of the underlying medium. When for some part of a fault plane the ratio of the stress to the pressure exceeds a certain strength level a stress-drop (‘a failure’) occurs (in accordance with the dry friction model), and it can cause a failure in other parts of the fault planes. In the model the failures represent earthquakes. As a result of the numerical simulation a synthetic earthquake catalog is produced. The numerical modelling was carried out for three types of structures with increasing of the structure separateness inside of each type and for two types of boundary movements. A synthetic earthquake flow is characterised by several features including the frequency-magnitude relation (the Gutenberg-Richter curve). When the structure separateness increases the slope of the curve changes monotonously in the same direction for all considered types of structures if the boundary movement is the same. The directions of changing of the slope are opposite for two considered boundary movements.