Modeling rupture propagation into creeping faults by thermal pressurisation

Victor Vescu, Oliver Stephenson, & Nadia Lapusta

Submitted September 7, 2025, SCEC Contribution #14954, 2025 SCEC Annual Meeting Poster #TBD

When a rupture reaches a region of slow slip, thermal pressurisation of pore fluids can enable rapid weakening and dynamic failure of the creeping zone (Noda and Lapusta, Nature, 2013). Previous results have shown that valid parameter combinations can allow a theoretical Mw 7.2 earthquake that propagates towards the creeping section to generate enough thermal pressurisation to rupture through this section. We use a highly simplified model of the simulated fault consisting of locked (velocity-weakening - VW) and creeping (velocity-strengthening - VS) segments, depth-averaged to consider only variations with its length and embedded within a 2-D linearly elastic isotropic medium. The fault is governed by a logarithmic rate-and-state friction law. The VS section additionally has thermal pressurisation (TP) of pore fluids due to shear heating, with the diffusion of heat and fluids from the fault. We vary three thermal pressurisation parameters (the coupling coefficient between temperature and pore pressure change, hydraulic diffusivity, and half-width of the actively shearing layer) to find the combinations that lead to dynamic rupture through the creeping region when the event size is large enough. For each parameter combination, we use theoretical considerations to estimate the amount of slip required for a positive stress drop to occur in the VS region. For those simulated events which ruptured the creeping section, we calculate the actual stress drop to verify the validity of the theoretical estimations. For those parameter combinations that give valid stress drops, we show that the ratio of the slip within the VW section and the estimated slip required for a positive stress drop can be correlated with whether the event ruptures the VS section or not.

Key Words
Thermal Pressurization, Parkfield, Rate-and-State Friction, Dynamic Weakening

Citation
Vescu, V., Stephenson, O., & Lapusta, N. (2025, 09). Modeling rupture propagation into creeping faults by thermal pressurisation. Poster Presentation at 2025 SCEC Annual Meeting.

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