Unstable Slip Pulses and Earthquake Nucleation as a Nonequilibrium First-Order Phase Transition

The onset of rapid slip along initially quiescent frictional interfaces, the process of “earthquake nucleation,” and dissipative spatiotemporal slippage dynamics play important roles in a broad range of physical systems. Here we first show that interfaces described by generic friction laws feature stress-dependent steady-state slip pulse solutions, which are unstable in the quasi-1D approximation of thin elastic bodies. We propose that such unstable slip pulses of linear size L^{∗} and characteristic amplitude are “critical nuclei” for rapid slip in a nonequilibrium analogy to equilibrium first-order phase transitions and quantitatively support this idea by dynamical calculations. We then perform 2D numerical calculations that indicate that the nucleation length L^{∗} exists also in 2D and that the existence of a fracture mechanics Griffith-like length L_{G}<L^{∗} gives rise to a richer phase diagram that features also sustained slip pulses.


Published in:
Physical Review Letters, 121, 23, 234302
Year:
Dec 07 2018
Laboratories:




 Record created 2018-12-11, last modified 2019-06-19

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