Earthquake nucleation on (aging) rate and state faults

We obtain quasi‐static, two‐dimensional solutions for earthquake nucleation on faults obeying Dieterich's “aging” version of the rate and state friction equations. Two distinct nucleation regimes are found, separated by roughly a / b ∼ 0.5, where a and b are the constitutive parameters relating changes in slip rate V and state θ to frictional strength. When fault healing is unimportant ( V θ/ D c ≫ 1, where D c is the characteristic slip distance for the evolution of θ), the nucleation zone spontaneously evolves toward a state of accelerating slip on a patch of fixed half length L ν ≈ 1.3774(μ′ D c / b σ), where μ′ is the intrinsic stiffness of the medium and σ is the normal stress. This is the fixed length…