Slow seismotectonic movements along the in- clined deep fault zone under the compressional horizontal stresses are supposed to be the prin- cipal mechanism controlling the structure and processes in the active ocean margins. Within the scope of the plane strain problem a simple 2-D geomechanical model for the evolution of an island arc system is investigated. We consider a homogeneous elastic half-plane with a shea- ring surface crack. The key element of the model is viscous interaction between the crack sides, the viscisity varying with depth. The model dif- fers from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and by possibly cyclical development of the transition zone._x000D_
A numerical modeling of the stress-strain state within the island arc system through time was carried out using a semianalytical approach._x000D_
The results of simulation are in good agreement with geological, geophysical, and seismological data.