Tidal Resonance Explains How Sun and Moon Trigger Slow Earthquakes
New research published in JGR Solid Earth proposes that gravitational tides from the Sun and Moon trigger slow earthquakes through a resonance mechanism. Although tidal stresses are minimal, comparable to a gentle hand press, they can nudge unstable fault lines into slipping. The study suggests that when tidal perturbation periods match a fault's natural response timescale, the resulting resonance amplifies slip, potentially leading to both slow and fast seismic events. This framework helps explain observed tremors in regions like southwest Japan and Cascadia, which often peak at 12- or 24-hour intervals. While the model focuses on single fault patches, it offers a method to reverse-engineer fault properties from seismic data, aiding in the assessment of megathrust earthquake risks.
