Multicycle earthquake rupture simulators generate long sequences of earthquakes along predefined fault geometries for statistical analysis of earthquake recurrence and related rupture characteristics. Based on the physical approximations of long‐term crustal deformation and the short‐term rupture process, they can provide a deeper understanding of the inner workings of the “earthquake machine” as well as inform seismic hazard assessment by filling the observational gap between instrumental seismology and paleoseismology. With MCQsim, we introduce a multi‐cycle rupture simulator that (a) can work with complex, nonplanar fault geometries and heterogenous models of fault strength, (b) includes different approximations of long‐term stress accumulation, (c) incorporates elastic signal propagation velocity, (d) distinguishes between stable, conditionally stable, and unstable portions of the fault, and (e) includes postseismic relaxation and afterslip. The generated earthquake catalogs allow the identification of parameters that dominate system behavior while also providing probabilities of future ruptures based on their preceding behavior. Here, we focus on the technical aspects of how MCQsim, which is based on elastostatic dislocation theory and the boundary element method, approximates both the seismic cycle and the earthquake’s rupture process. We provide exemplary simulation outputs for verification and validation purposes.

https://doi.org/10.1785/0120220248