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Experimental and Numerical Modelling of Deformation and Fluid Flow |
1 Grant Institute, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JW, UK
2 Géosciences Rennes, UPR 4661 du CNRS, Campus de Beaulieu, 35042 Rennes Cedex, France
* Département de Géologie, Université de Cergy-Pontoise, Le campus, 8, Av. du Parc, 95 033 Cergy-Pontoise Cedex, France
Fault growth in brittle media has previously been extensively studied via a numerical approach using scalar representation of the stress and strain fields. More realistic simulations and further investigations of fault array evolution demand a fully tensorial three dimensional (3D) representation of these fields. In this paper we present a tensorial model of the spontaneous birth and growth of faults in a 3D medium. The medium is elastic and attenuating up to a stress threshold, determined by the Mohr-Coulomb criterion, where brittle failure is modelled by a partial shear stress drop. Elastic radiations generated by the rupture are explicitly extrapolated in time by a finite-difference scheme of the equation of dynamics until the static state is reached. We do not consider the dynamic process explicitly; further ruptures can only be triggered by the resulting static stress field, or by the imposed straining of the medium. Preliminary simulations of 3D straining of a 2D plate show how a pre-existing fault set (appearing as a perturbed stress field)can influence the development of a second fault set. We believe that our model provides a valuable tool for the study of fault development and in particular for the assessment of the effects of anisotropic stresses around faults on strain accumulation and the spatial organization of crustal deformation.
