Analysis of slip-weakening frictional laws with static restrengthening and their implications on the scaling, asymmetry and mode of dynamic rupture on homogeneous and bi-material interfaces

摘要

Dynamic simulations of homogeneous and heterogeneous fault rupture using the finite element method are presented giving rise to both crack-like and pulse-like rupture. We employ various slip-weakening frictional laws to examine their effect on the resulting earthquake rupture speed, size and mode. More complex rupture characteristics were produced with more strongly slip-weakening frictional laws, and the degree of slip-weakening had to be finely tuned to reproduce realistic earthquake rupture characteristics. Rupture propagation on a fault is controlled by the constitutive properties of the fault. A dynamic elasto-plastic constitutive law for the interface friction at the fault is formulated based on the Coulomb failure criterion and applied in a way analogous to non-associated elasto-plasticity. We provide benchmark tests of our method against other reported solutions in the literature. We demonstrate the applicability of our elasto-plastic fault model for modeling dynamic rupture and wave propagation in fault systems, and the rich array of dynamic properties produced by our elasto-plastic finite element fault model. These are governed by a number of model parameters including: the spatial and material heterogeneity of the fault, the fault strength, and not least of all the frictional law employed. Asymmetric bilateral fault rupture was produced for the heterogeneous case, where the degree of heterogeneity influenced the rupture speed in the different propagation directions.