Study Models How Tidal Forces Can Trigger Slow Earthquakes on Stable Faults
Researchers used computational models to investigate how tidal stress from the Moon and Sun can trigger seismic slip events on faults that are normally stable. The study found that even small stress perturbations can cause periodic or complex slip patterns, with triggering behavior controlled by the timing and magnitude of tidal forces. Understanding these mechanisms could help scientists identify which fault zones are sensitive to small stress changes and better constrain fault properties.
A new theoretical study employs spring-block models with rate-and-state friction to examine how tidal stresses trigger earthquakes on velocity-weakening stable sliding faults. Using both step and harmonic stress perturbations, the researchers identified key parameters controlling tidal triggering, including the normalized perturbation period and amplitude. The results demonstrate that small stress perturbations can generate both periodic and temporally complex slip events. Notably, increasing the normalized period shifts event timing from peak tidal stress toward peak stress rate, while increasing amplitude promotes transitions from slow to fast events. The framework explains observed phase preferences between tidal stress and slip velocity, and the authors suggest that comparing model predictions with observed tidal correlation patterns could constrain the frictional strength of fault interfaces and characteristic slip distances.
What's missing
The study does not discuss the relative frequency or magnitude of tidal triggering compared to other triggering mechanisms (e.g., internal stress accumulation, fluid pressure changes). Additionally, the applicability of the spring-block model to real-world fault geometries and heterogeneous stress distributions is not addressed. The paper also does not provide quantitative predictions for which specific fault zones worldwide might be most susceptible to tidal triggering.
What different sources said
- arXiv physicsCenter
Theoretical constraints on tidal triggering of slow earthquakes
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