Thermo-mechanical models of seismic swarms at oceanic transform faults

Mingqi Liu, & Sylvain D. Barbot

Published September 10, 2023, SCEC Contribution #12788, 2023 SCEC Annual Meeting Poster #124

Oceanic transform faults form an ideal environment for studying earthquake behavior because of the simple thermal and kinematic structure, short earthquake cycles, and high levels of aseismic slip. Slow transforms are characterized by a lower temperature and a thin crust with a serpentinized mantle. In contrast, the fast oceanic transform features a thick crust with a wide area affected by fracturing and high porosity at a higher temperature. Fluid-filled area with a serpentinized mantle stops the propagation of large earthquakes and produces seismic warms. However, the earthquake behavior is not well constrained and the earthquake rupture process remains elusive. In this study, we mainly investigate the earthquake rupture process at transform faults using numerical simulations of the seismic cycle. We use a thermo-mechanical model to constrain the thermal and lithological conditions that govern the constitutive behavior of fault friction. We simulate the rupture initiation and propagation through a physics-based rate- and state-dependent constitutive law for fault slip with temperature effects. Two-dimensional models reveal that earthquake swarms may form at a large Dieterich-Ruina-Rice number (Ru > 25) with thermal strengthening or at a small Ru (<15) with thermal weakening. Three-dimensional models suggest that, due to the interaction from the adjacent seismic patches, the fault friction should be weaker than that in 2D models to produce earthquake swarms at the barrier zone. In addition, the narrow velocity strengthening zone caused by the stepover is a possible mechanism to prohibit the interaction and facilitate the earthquake swarms. Next, we compare our findings with the seismogenic behavior at the Gofar and Blanco transform faults. Our study could improve our understanding of how oceanic transform faults moves and how lithospheric composition affects the earthquake rupture process.

Key Words
Seismic cycle, transfrom fault, earthquke swarms

Citation
Liu, M., & Barbot, S. D. (2023, 09). Thermo-mechanical models of seismic swarms at oceanic transform faults. Poster Presentation at 2023 SCEC Annual Meeting.

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