Models of Sequences of Earthquakes and Aseismic Slip with Off-fault Plasticity Show Frequent Rupture Jumps and Seismic Complexity in Fault Zones with Tensile Step-Overs

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

Published September 10, 2023, SCEC Contribution #13129, 2023 SCEC Annual Meeting Poster #134

Fault step-overs are prime examples of geometric complexity in natural faults which can enhance the risk of seismic hazards through rupture jumping. However, the long-term pattern of seismicity in the fault step-overs and underlying mechanisms of rupture jumping in the context of earthquake cycles are rarely studied. Leveraging a hybrid numerical scheme combining the finite element and the spectral boundary Integral methods, FEBE, we carry out fully dynamic simulations of Sequences of Earthquakes and Aseismic Slip (SEAS) for both compressive and tensile step-over with off-fault plasticity. We consider rate-and-state friction law for the fault friction, and pressure sensitive Drucker-Prager plasticity for the off-fault bulk response. We observe the accumulation of plasticity, an indication of off-fault damage, is significantly different in the two cases with more plasticity projected in the overlapping gap region for the tensile step-over. The seismic pattern for tensile step-over is more complex in comparison with the compressive one as well as with its elastic counterparts. The tensile step-over with off-fault plasticity shows rupture segmentation, temporal clustering, and frequent rupture jumping from one fault to another. The source characteristics of the jumped events are sometimes comparable to the rupture in a straight through-going fault even though the length of each fault in the step-over is only around half of the straight fault. These results may have a crucial role in illuminating the possible mechanism of rupture jumping in fault step-overs as well as its long-term evolution.

Citation
Mia, M., Abdelmeguid, M., & Elbanna, A. E. (2023, 09). Models of Sequences of Earthquakes and Aseismic Slip with Off-fault Plasticity Show Frequent Rupture Jumps and Seismic Complexity in Fault Zones with Tensile Step-Overs. Poster Presentation at 2023 SCEC Annual Meeting.

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