Numerical modeling of block structure dynamics: an arc subduction zone

The dynamics of a block structure approximating an are subduction zone, whi ch is typical for regions of island arcs, was simulated numerically. The mo del used for simulation consists of absolutely rigid blocks separated by in finitely thin plane faults. Velocity vectors are specified to define the mo tion of the oceanic plate and the medium underlying the continent during th e simulation. The interaction of the blocks along fault planes and with the underlying medium is viscous-elastic. When the ratio of the stress to the normal stress exceeds a certain strength level for some part of a fault, a stress-drop ('a failure') occurs in accordance with the laws of dry frictio n; it can cause failure in other parts of the same fault or within other fa ults. In the model, the failures represent earthquakes, so a synthetic eart hquake catalog is produced. The computations, carried out with different di p angles of the subduction zone and directions of the movement of the ocean ic plate, show that the seismic activity in the model is maximal when the d ip angle of the subduction zone is about 40-50 degrees. The synthetic seism icity migrates along the are of the subduction zone. (C) 1999 Elsevier Scie nce B.V. All rights reserved.