Coevolution of Fault Zones and Earthquakes in a Multi-Cycle Simulation of Fault Networks

Ahmed E. Elbanna, Md Shumon Mia, & Mohamed Abdelmeguid

Submitted September 10, 2023, SCEC Contribution #13123, 2023 SCEC Annual Meeting Poster #100

Fault networks are more prevalent in geologic environments posing significant seismic hazard. Understanding the pattern of seismicity in such complex fault zones as well as their evolution is crucial in developing seismic hazard models and in guiding plans for societal preparedness. Here, we simulate fully dynamic sequences of earthquakes and aseismic slip (SEAS) for a network of faults in an elastoplastic fault zone. The network consists of a main fault and surrounding short branches with different sizes and orientations. For a 2D plane strain model with rate-and-state friction and off-fault plasticity, we employ a hybrid numerical scheme combining the finite element and the spectral boundary integral methods (FEBE). Simulation results show that activation happens in some of the branches during seismic events in the main fault. Activation of branches also influences the rupture characteristics and seismicity pattern in the main fault with rupture segmentation and aperiodicity. Furthermore, we observe higher or lower activation depending on the orientation of background stress. Seismicity is more concentrated on the main fault with less favorable orientation of stress with respect to the branches. For more favorable stress orientation, the branches are more prone to slip frequently with less seismicity on the main fault. The plastic strain evolution shows higher concentration of plasticity at the ends of the activated branches and heterogeneous distribution along the main fault strike. The evolution of plastic strain is indicative of how the fault network may evolve in space and time and attests to the non-equilibrium nature of the problem. Our findings shed new lights on the coevolution of fault zone and seismicity over different spatial and temporal scales, uncover new insights into source characteristics, and contribute to further development of seismic hazard models.

Elbanna, A. E., Mia, M., & Abdelmeguid, M. (2023, 09). Coevolution of Fault Zones and Earthquakes in a Multi-Cycle Simulation of Fault Networks. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)