Numerical study of the role of localized stress perturbations on fault slip: Insights for injection-induced fault reactivation

We used numerical methods and the rate-and-state dependent friction law to investigate the role of localized stress perturbation, as a simple analog of fluid overpressure caused by fluid injection, on pre-existing fault. The failure stress exceeds that predicted by the Coulomb failure criterion, inversely proportional to the size of the perturbation zone and the criticality of the tectonic stress on the fault, but proportional to stressing rate. The size and spatial distribution of perturbation relative to the velocity weakening zone strongly impact rupture timing, location, and size. Broadly distributed pressurization can lead to rupture well before reaching the reference failure stress without perturbation. When the perturbation stress is applied at a critically stressed fault or segment, the rupture runs away beyond the perturbation zone. Conversely, the rupture is self-arrested and limited within the perturbation zone. If the fault contains multiple segments, diversified rupture patterns, in addition to normal earthquakes, doublet events, and slow slips, are sometimes observed, even in the velocity-weakening zones.

Automated summary

The study investigates the role of localized stress perturbation on pre-existing fault using numerical methods and rate-and-state dependent friction law. Results show that the failure stress is inversely proportional to the size of the perturbation zone and the criticality of the tectonic stress on the fault, but proportional to stressing rate. Additionally, the size and spatial distribution of perturbation relative to the velocity weakening zone strongly impact rupture timing, location, and size.