Do Large Earthquakes along Major Faults Synchronize in Time?

The triggering mechanism of earthquakes and their synchronization in time and space can be considered the two sides of the same coin. Our previous studies on earthquake triggering reveal sensitive parameters affecting the triggering mechanism using simple spring slider systems. We pursue our previous analyses by considering a simulation set-up for synchronizing three strong asperity patches on a vertically oriented strike-slip fault with initial slip heterogeneity separated by barriers and strong creeping regions at the edges. This analogy intends to explore earthquake synchronization in time and mimic observed sequences of large earthquakes that ruptured most of the North Anatolian Fault within short time intervals. Using the quasi-dynamic and full-dynamic pseudo-spectral Fast Fourier Transform (FFT) method, we apply a periodic fault model governed with Rate-and-State Friction (RSF) law embedded in a 2.5D continuum. Simulation results so far using the quasi-dynamic approach revealed that the earthquake synchronization is mainly affected by direct velocity effect parameters, barrier dimension/properties, and RSF law (aging and slip law), particularly the weakening terms. Lower direct velocity effect parameters, state evolutions with a stronger weakening term such as slip law, and shorter barrier lengths promote better synchronization. In this respect, we observed fast, slow, or no synchronization depending on the parameter sets. It is also worth noting that slip localizes in the continuum at small critical slip distances, which cannot be inferred from simple 1D models, suggesting the size dependence. In order to minimize inherent non-uniqueness and uncertainties, the same set-up will also be simulated with the full-dynamic approach in which wave-mediated stress transfer is taken into account, and the long-term earthquake histories will be correlated with case-specific simulations.