Some insights on dynamic rupture modelling using a finite element method
Résumé
Finite element methods (FEM), as often used in soil dynamics should be a powerful tool to simulate the dynamic rupture process on earthquake faults, allowing us to take into account the asymmetry of fault geometry with respect to the ground surface as well as material heterogeneity with inelastic properties. A FEM program to model non-linear elastodynamics, GEFDYN, is used to model rupture propagation on a seismic fault. The fault is simulated using "joint-elements" that are thin and flat and may be programmed to simulate a number of frictional properties. We perform preliminary simulations on a single plane fault embedded in a 2D homogeneous unbounded elastic media and compare results with those of a boundary integral equation method. Under uniform initial stress conditions, we release certain amount of stress on a small area of the fault and the dynamic rupture progresses spontaneously controlled by the plastic behaviour of joint-elements used to simulate the Coulomb friction law on the fault. The formulation of the joint elements, as well as the parameters of their constitutive model are analysed and discussed, such as the shear elastic modulus Gjoint. We find it important to carefully treat these joint-elements to obtain the accurate solutions. With these tests, we demonstrate that this tool constitutes an appropriate model to study dynamic rupture propagation on a fault.