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

Shiqing Xu, Yehuda Ben-Zion, & Jean-Paul Ampuero

Published December 2012, SCEC Contribution #1705

We discuss results associated with 2D 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 while 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 of the background maximum compressive stress relative to the fault and the crack vs. 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 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.

Xu, S., Ben-Zion, Y., & Ampuero, J. (2012). Properties of inelastic yielding zones generated by in-plane dynamic ruptures: I. model description and basic results. Geophysical Journal International, 191(3), 1325–1342. doi: 10.1111/j.1365-246X.2012.05679.x.