Fault Segmentation Pattern Controlled by Thickness of Brittle Crust

During large earthquakes, seismic sources tend to split in several sub-events that rupture neighboring fault patches called segments. The scaling of such segmentation plays a decisive role earthquake dynamics, especially for strike-slip events. Using numerical modeling we demonstrate when pristine layer brittle material is sheared, the first oblique Riedel fractures nucleate with regular spacing controlled by thickness layer. later localization deformation, those initial control spatial structuration entire system. Analyzing horizontal stress distribution fault-parallel direction different ratios between inter-Riedel distance and thickness, identify threshold at 1.5, beyond which switches from compressional tensional leads nucleation new fracture. Thus, segment length appears be vertical along fault.