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

Valere R. Lambert, Brittany A. Erickson, Junle Jiang, Eric M. Dunham, Mohamed Abdelmeguid, Mary Agajanian, Martin Almquist, Jean-Paul Ampuero, Ryosuke Ando, Sylvain D. Barbot, Segun Steven Bodunde, Camilla Cattania, Alexandre Chen, Luca Dal Zilio, Benchun Duan, Ahmed E. Elbanna, Alice-Agnes Gabriel, Yihe Huang, Yoshihiro Kaneko, Taeho Kim, Jeremy E. Kozdon, Nadia Lapusta, Duo Li, Meng Li, Chao Liang, Dunyu Liu, Yajing Liu, Jasper Marcum, Md Shumon Mia, So Ozawa, Casper Pranger, Pierre Romanet, Paul Segall, Yudong Sun, Prithvi Thakur, Carsten Uphoff, Ylona van Dinther, Roos Verwijs, & Yuyun Yang

Submitted September 10, 2023, SCEC Contribution #12930, 2023 SCEC Annual Meeting Poster #135

Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have rapidly progressed over recent decades to address fundamental problems in earthquake physics and fault mechanics. Challenges in SEAS modeling remain in resolving the multiscale interactions between slow slip, earthquake nucleation, and dynamic rupture; and understanding physical factors that control 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. We achieve excellent agreement between simulations from a growing cohort of modeling groups for a range of 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 (Erickson et al., 2020; Jiang et al., 2022; Erickson et al., 2023). These comparisons allow us to assess relative sensitivities of simulated short- and long-term fault processes as well as different observables, including recurrence intervals, surface displacements, and statistics of simulated earthquakes, to numerical factors, such as treatments of the computational domain, boundary conditions, and numerical resolution. Our recent benchmarks 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 evolution laws for fault friction. We utilize simulations from different groups to explore how various numerical factors, such as methods for time-stepping and transitioning between quasi-static and dynamic solvers, affect the resolved interaction between aseismic and seismic processes, as well as changes in pore fluid pressure. 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 SEAS models and their integration with geophysical observations, ultimately contributing to an improved understanding of earthquake system dynamics.

Key Words
Earthquakes, aseismic slip, crustal deformation, fluids, numerical modeling, code verification

Citation
Lambert, V. R., Erickson, B. A., Jiang, J., Dunham, E. M., Abdelmeguid, M., Agajanian, M., Almquist, M., Ampuero, J., Ando, R., Barbot, S. D., Bodunde, S., Cattania, C., Chen, A., Dal Zilio, L., Duan, B., Elbanna, A. E., Gabriel, A., Huang, Y., Kaneko, Y., Kim, T., Kozdon, J. E., Lapusta, N., Li, D., Li, M., Liang, C., Liu, D., Liu, Y., Marcum, J., Mia, M., Ozawa, S., Pranger, C., Romanet, P., Segall, P., Sun, Y., Thakur, P., Uphoff, C., van Dinther, Y., Verwijs, R., & Yang, Y. (2023, 09). Community Code Verification Exercises for Simulations of Earthquake Sequences and Aseismic Slip (SEAS): Effects from Dipping Faults and Full Elastodynamics to Fluids and Fault Friction Evolution. Poster Presentation at 2023 SCEC Annual Meeting.

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