NUMERICAL MODELING OF BLOCK-STRUCTURE DYNAMICS - APPLICATION TO THE VRANCEA REGION

A seismically active region is modelled as a system of absolutely rigi d blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is v iscous-elastic. The system of blocks moves as a consequence of prescri bed motion of the boundary blocks and of the underlying medium. When, for some part of a fault plane the stress exceeds a certain strength l evel, a stress-drop (''a failure'') occurs, and it can cause failures in other parts of the fault planes. In our model the failures represen t earthquakes. As a result of the numerical simulation a synthetic ear thquake 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 numeri cal experiment is a synthetic earthquake catalog with the space distri bution of epicenters close to the real distribution and the frequency- magnitude relations (Gutenberg-Richter curves) obtained for the synthe tic and real catalogs possessing some common features.