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Geophysical Research Abstracts Vol. 19, EGU2017-9939, 2017 EGU General Assembly 2017 © Author(s) 2017. CC Attribution 3.0 License. Influence of fault heterogeneity on the frequency-magnitude statistics of earthquake cycle simulations Jack Norbeck (1,2) and Roland Horne (1) (1) Stanford Center for Induced and Triggered Seismicity, Stanford University, Stanford, California, USA, (2) Earthquake Science Center, United States Geological Survey, Menlo Park, California, USA Numerical models are useful tools for investigating natural geologic conditions can affect seismicity, but it can often be difficult to generate realistic earthquake sequences using physics-based earthquake rupture models. Rate-and-state earthquake cycle simulations on planar faults with homogeneous frictional properties and stress conditions typically yield single event sequences with a single earthquake magnitude characteristic of the size of the fault. In reality, earthquake sequences have been observed to follow a Gutenberg-Richter-type frequencymagnitude distribution that can be characterized by a power law scaling relationship. The purpose of this study was to determine how fault heterogeneity can affect the frequency-magnitude distribution of simulated earthquake events. We considered the effects fault heterogeneity at two different length-scales by performing numerical earthquake rupture simulations within a rate-and-state friction framework. In our first study, we investigated how heterogeneous, fractal distributions of shear and normal stress resolved along a two-dimensional fault surface influenced the earthquake nucleation, rupture, and arrest processes. We generated a catalog of earthquake events by performing earthquake cycle simulations for 90 random realizations of fractal stress distributions. Typical realizations produced between 4 to 6 individual earthquakes ranging in event magnitudes between those characteristic of the minimum patch size for nucleation and the size of the model fault. The resulting aggregate frequency-magnitude distributions were characterized well by a power-law scaling behavior. In our second study, we performed simulations of injection-induced seismicity using a coupled fluid flow and rate-and-state earthquake model. Fluid flow in a two-dimensional reservoir was modeled, and the fault mechanics was modeled under a plane strain assumption (i.e. one-dimensional faults). We generated a set of faults with an average strike of +/- 30 degrees from the direction of maximum principal stress and with a fractal distribution of lengths. The faults were randomly prescribed an initial shear stress ranging between critically-stressed and subcritically-stressed within one stress drop. High-rate injection into a single well in an infinite reservoir ultimately triggered a sequence of earthquakes. We investigated the sensitivity of the frequency-magnitude statistics to the different distributions of fault sizes and initial proximity to failure.