Community Code Verification Exercises for Simulations of Earthquake Sequences and Aseismic Slip (SEAS): Effects from Fluids and Fault Friction Evolution

Valere R. Lambert, Brittany A. Erickson, Junle Jiang, Eric M. Dunham, Taeho Kim, Mary Agajanian, Jean-Paul Ampuero, Ryosuke Ando, Frederic Cappa, Camilla Cattania, Benchun Duan, Pierre Dublanchet, Ahmed E. Elbanna, Yuri Fialko, Alice-Agnes Gabriel, Piyush Karki, Nadia Lapusta, Duo Li, Meng Li, Dunyu Liu, Yohai Magen, Jasper Marcum, Dave A. May, Md Shumon Mia, So Ozawa, Casper Pranger, Pierre Romanet, Marco M. Scuderi, Prithvi Thakur, Ylona van Dinther, Roos Verwijs, Yuyun Yang, & Jeena Yun

Submitted September 7, 2025, SCEC Contribution #14466, 2025 SCEC Annual Meeting Poster #TBD

Numerical simulations of Sequences of Earthquakes and Aseismic Slip (SEAS) have rapidly progressed to address fundamental problems in fault mechanics and provide self-consistent, physics-based frameworks to interpret and predict geophysical observations across spatial and temporal scales. Challenges in SEAS modeling include resolving the multiscale interactions between slow slip, earthquake nucleation, and dynamic rupture; and understanding the physical factors controlling observables such as seismicity and deformation. To advance SEAS simulations with rigor and reproducibility, we pursue community efforts to verify numerical codes in an expanding suite of benchmarks, including problems considering earthquake sequences on 2D and 3D fault models obeying rate-and-state friction with different treatments of inertial effects and fault dip under slow tectonic loading.

Here we present code comparison results from a new set of benchmark problems that focus on aseismic processes and earthquake nucleation, including the influence of (1) changes in effective normal stress and pore fluid pressure due to fluid injection and diffusion and (2) different formulations of fault friction, including rate-and-state fault models using the aging and slip law formulations for frictional state evolution, as well as a constant friction coefficient. We utilize simulations from different groups to explore how various numerical factors affect the simulated evolution of pore pressure and interaction between aseismic and seismic processes. We achieve excellent quantitative agreement across participating codes that utilize distinct numerical methods, by ensuring sufficiently fine time-stepping, large enough domain size for volumetric methods and consistent treatment of boundary conditions. Through these comparative studies, we seek to determine best practices for improving the accuracy and efficiency of SEAS simulations and develop quantitative metrics for benchmarking modeling results. These community-led exercises will foster the development of more realistic multi-physics SEAS models and their integration with geophysical observations, contributing to an improved understanding of fault dynamics.

Citation
Lambert, V. R., Erickson, B. A., Jiang, J., Dunham, E. M., Kim, T., Agajanian, M., Ampuero, J., Ando, R., Cappa, F., Cattania, C., Duan, B., Dublanchet, P., Elbanna, A. E., Fialko, Y., Gabriel, A., Karki, P., Lapusta, N., Li, D., Li, M., Liu, D., Magen, Y., Marcum, J., May, D. A., Mia, M., Ozawa, S., Pranger, C., Romanet, P., Scuderi, M. M., Thakur, P., van Dinther, Y., Verwijs, R., Yang, Y., & Yun, J. (2025, 09). Community Code Verification Exercises for Simulations of Earthquake Sequences and Aseismic Slip (SEAS): Effects from Fluids and Fault Friction Evolution. Poster Presentation at 2025 SCEC Annual Meeting.

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