The paper reports the results of 3D numerical modeling of fault structure formation in a layer of a geomedium under strike-slip displacement of the basement blocks. It is shown that the structure of fracture zones mostly depends on the initial stress state induced by gravity. In a high-strength medium, when the initial state is elastic, localization Riedel bands and a vertical fault can be formed. In case if initial stresses are close to the elastic limit or the lower part of rock goes to the inelastic state, a more complex flower structure of faults is formed
