Partial ruptures, cascading multi-fault ruptures, and aftershocks in 2D random fault network

The Gutenberg-Richter law for the distribution of earthquake magnitude and the Omori law for the decay of aftershocks are two universal laws in seismicity. Although numerical models have been developed to reproduce these laws, they sometimes produce many more foreshocks and less aftershocks than observed. In this study, we simulate earthquake sequences on a 2D random fault network. The fault lengths follow a power-law distribution. Our simulations reproduce the Omori law, without producing many foreshocks. The event size distribution follows Gutenberg-Richter's law with the b-value expected from the fault length distribution, even though many earthquakes are multi-fault ruptures or partial ruptures. Ruptures sometimes propagate into other faults, though there are more partial ruptures than multi-fault ruptures. The frequency of partial and cascading ruptures increases with higher fault density or stronger velocity-weakening friction. Overall, this work illuminates how fault interaction controls the spatiotemporal pattern of seismicity.