MC-QSim -- Introducing a new multi-cycle earthquake rupture simulator

Olaf Zielke, & Paul Martin Mail

Published July 29, 2019, SCEC Contribution #9282, 2019 SCEC Annual Meeting Poster #026

With this abstract, we introduce MC-QSim, a newly formulated multi-cycle earthquake rupture simulator for the generation of long sequences of earthquakes along arbitrarily complex fault geometries with heterogeneous distributions of fault constitutive parameters. The goal of this simulator is to provide a tool for comprehensive parameter space investigations that assess the system's behavior and sensitivity to varying combinations of fault geometry and parameter distributions. It will further serve to assess the probability of future earthquakes along actually existing fault geometries, based on past observations along these faults and current (i.e., implemented) knowledge of inter-, co-, and post-seismic phase. In that regard, it is meant to serve as an alternative to existing multi-cycle rupture simulators such as AllCal, RSQsim, Virtual California, or ViscoSim –providing a different representation of the underlying physics.

MC-QSim is a quasi-dynamic rupture simulator, utilizing the artifact-free analytical solutions by Nikkhoo and Walter (2015) for triangular dislocations. It accounts for the temporal aspects of the rupture process and stress propagation, generating source-time functions for individual fault cells as well as moment-rate functions for the entire earthquake that may be imported into wave propagation codes. It features three different friction laws (Coulomb, slip-weakening, velocity-weakening). The strength of faults as well as the constitutive parameters of fault friction may vary spatially (and temporally) along the fault to create stable, conditionally stable, or unstable fault cells (e.g., with locked and unlocked fault portions within the seismogenic zone) where the prior two may exhibit after-slip. The simulator incorporates the epistemic uncertainties in fault geometry and parameter distribution along the fault by allowing to automatically generate input models in which these parameters may vary randomly within a predefined range (e.g., fault roughness and fault strength represented as random fields). Analyzing the corresponding suite of earthquake catalogs will provide a more comprehensive representation of possible and likely rupture behavior along the investigated fault (system), accounting for the aforementioned uncertainties. Finally, the simulator code is fully parallelized and runs on laptop PCs as well as large-scale computer infrastructures (e.g., SHAHEEN 2 at KAUST).

Key Words
rupture simulation, multi-cycle, earthquake sequence

Citation
Zielke, O., & Mail, P. (2019, 07). MC-QSim -- Introducing a new multi-cycle earthquake rupture simulator. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)