Numerical Modelling of Block-structure Dynamics: Application to the Vrancea Region

—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 stress exceeds a certain strength level, a stress-drop ("a failure") occurs, and it can cause failures in other parts of the fault planes. In our model the failures represent earthquakes. As a result of the numerical simulation a synthetic earthquake catalog is produced. ? The procedure is applied to the numerical modelling of the dynamics of the block-structure, which approximates the tectonic structure of the Vrancea region. The result of the numerical experiment is a synthetic earthquake catalog with the space distribution of epicenters close to the real distribution and the frequency-magnitude relations (Gutenberg-Richter curves) obtained for the synthetic and real catalogs possessing some common features.