Formation and evolution of a population of strike-slip faults in a multiscale cellular automaton model | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Formation and evolution of a population of strike-slip faults in a multiscale cellular automaton model

Type de publication:

Journal Article

Source:

Geophysical Journal International, Volume 168, Ticket 2, p.723-744 (2007)

ISBN:

0956-540X

URL:

http://www.blackwell-synergy.com/

Mots-clés:

ORGANIZATION; CALIFORNIA; TECTONICS; DYNAMICS; FRACTURE; GROWTH

Résumé:

<p>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. In these numerical simulations, the material properties are uniform, so the entire process of fault development arises spontaneously from the pattern of interactions between the elements of the system over time. Furthermore, homogenization of the strain rate along faults and structural regularization of the fault trace can be quantified by analysis of the output patterns. The time dependent stochastic process allows relocation of faults by branching from bends and irregularities of the fault traces. This relocation mechanism involves partitioning of the strain and competition between faults. Possible relationships between the seismic regime and the geometry of the fault population suggest that the fault system may be attracted by a critical point. Towards this critical point, the correlation length (i.e. the length of the largest fault) increases, the proportion of large event is higher and larger faults are able to slip at lower stresses.</p>

Notes:

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