Geophys. J. Int. (2007) 168, 723–744 doi: 10.1111/j.1365-246X.2006.03213.x Formation and evolution of a population of strike-slip faults in a multiscale cellular automaton model Cl´ement Narteau Laboratoire de Dynamique des Syst`emes G´eologiques, Institut de Physique du Globe de Paris, 4, Place Jussieu, Paris, Cedex 05, 75252, France. E-mail:
[email protected] Accepted 2006 September 4. Received 2006 September 4; in original form 2004 August 10 SUMMARY This paper describes a new model of rupture designed to reproduce structural patterns observed in the formation and evolution of a population of strike-slip faults. This model is a multiscale cellular automaton with two states. A stable state is associated with an ‘intact’ zone in which the fracturing process is confined to a smaller length scale. An active state is associated with an actively slipping fault. At the smallest length scale of a fault segment, transition rates from one state to another are determined with respect to the magnitude of the local strain rate and a time-dependent stochastic process. At increasingly larger length scales, healing and faulting are described according to geometric rules of fault interaction based on fracture mechanics. A redistribution of the strain rates in the neighbourhood of active faults at all length scales ensures that long range interactions and non-linear feedback processes are incorporated in the fault growth mechanism. Typical patterns of development of a population of faults are presented and show nucleation, growth, branching, interaction and coalescence. The geometries of the fault populations spontaneously converge to a configuration in which strain is concentrated on a dominant fault.