Direct observation of emerged fault surface as well as results of inversions show that heterogeneity on fault is present at all scales. This leads to investigate the feasibility of including the effects of heterogeneities smaller than the grid step size in dynamics rupture simulations.

Rupture of heterogeneous faults are simulated thanks to numerical three-dimmensional modeling. The measurement of the slip on the fault during the initiation phase of the rupture permits to construct an effective friction law. When applied on a homogeneous fault, this friction law reproduces the main features of the rupture of the heterogeneous fault. In multi-scale heterogeneous model, the smallest heterogeneity can be replaced by the effective friction law, and the temporal evolution of the rupture process is preserved.

This method permits to reproduce the physical effects of small scale heterogeneity in dynamic rupture simulations without reducing the grid step. It is therefore very cost effective. Finally, this work constitutes a first step towards the understanding of the scale dependence of friction parameters, bridging the gap between laboratory and seismic measurements.