Dynamic Slip in 2D Discrete Element Method Numerical Simulations of a Rough Fault
Abstract
2D discrete element method (DEM) simulations are used to investigate the properties of the dynamic rupture of a heterogeneous fault. The model consists of two rectangular blocks of fully bonded particles with a preexisting fault between the blocks across which the particles are not bonded and interact only by frictional forces. An intrinsic small scale roughness of the fault surface is present due to the construction of the fault model from random spherical particles. Additionally, heterogeneity on a large length scale is introduced, generating asperity and nonasperity regions along the fault by varying the amount of smallscale surface roughness between these regions. Contact friction is defined using a Coulomb Law. The model evolves from a stressfree initial state into stickslip behaviour while a constant normal stress and a constant shear velocity are applied to the edges of the model. The resulting slip events show a number of properties similar to real seismic events. We observe qualitatively realistic sourcetime functions, although the absolute slip velocities are too high, realistic stress drops and rupture velocities. The power spectral density (PSD) of the resulting slip distributions is consistent with a fractal distribution, as observed in nature. The results indicate that a simple friction law coupled with geometrical complexity yields many of the characteristic features seen in real rupture propagation.
 Publication:

AGU Fall Meeting Abstracts
 Pub Date:
 December 2007
 Bibcode:
 2007AGUFM.S21B0572A
 Keywords:

 7209 Earthquake dynamics (1242);
 7290 Computational seismology;
 8118 Dynamics and mechanics of faulting (8004)