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Published December 2012 | Published
Journal Article Open

Properties of inelastic yielding zones generated by in-plane dynamic ruptures—I. Model description and basic results


We discuss results associated with 2-D numerical simulations of in-plane dynamic ruptures on a fault governed by slip-weakening and rate-and-state friction laws with off-fault yielding. The onset of yielding is determined by a Mohr–Coulomb-type criterion whereas the subsequent inelastic response is described by a Duvaut-Lions-type viscoplastic rheology. The study attempts to identify key parameters and conditions that control the spatial distribution and the intensity variation of off-fault yielding zones, the local orientation of the expected microfractures, and scaling relations or correlations among different quantities that can be used to characterize the yielding zones. In this paper, we present example results for crack and pulse ruptures, along with calculations of energy partition and characteristics of the simulated off-fault yielding zones. A companion follow-up paper provides a comprehensive parameter-space study of various examined features. In agreement with previous studies, the location and shape of the off-fault yielding zones depend strongly on the angle ψ of the background maximum compressive stress relative to the fault and the crack versus pulse mode of rupture. Following initial transients associated with nucleation of ruptures, the rate of various energy components (including off-fault dissipation) linearly increases with time for cracks, while approaching a constant level for pulse-like ruptures. The local angle to the fault of the expected microfractures is generally shallower and steeper than ψ in the compressional and extensional quadrants, respectively. The scalar seismic potency density decays logarithmically with increasing fault normal distance, with decay slope and maximum value that are influenced by the operating stress field.

Additional Information

© 2012 The Authors. Geophysical Journal International © 2012 RAS. Accepted 2012 September 13. Received 2012 July 4; in original form 2012 February 8. Article first published online: 26 Oct. 2012. We thank Massimo Cocco, an anonymous referee and Editor Xiaofei Chen for useful comments. The study was supported by the National Science Foundation (grants EAR-0944066 and EAR-0908903) and the Southern California Earthquake Center (based on NSF Cooperative Agreement EAR-0529922 and USGS Cooperative Agreement 07HQAC0026).

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