If the healing rate is rapid, a network of disordered faults is obtained, while if the rate is slow, the fault systems are more regular. If earthquakes are introduced into the above model, the transverse segment ruptures infrequently in comparison with the strike-slip sections. The fault system is much more heterogeneous. Li and Ben-Zion have found that the stress correlation lengths fluctuate with time on a spatially heterogeneous fault. The correlation lengths are small after a large event and increase in the early times after a large event.
Energy is given by an integral of stress drop times displacement over the rupture surface.
Its approximation by the product of average slip times average stress drop times area is particularly inappropriate for an asperity model of fracture since large slips may take place in low stress-drop regions. The ratio of strain energy to seismic moment can differ by as much as a factor of 3 from expectations for a classical barrier model of fracture.