Research published in JGR Solid Earth in 2026 reveals that tidal forces from the Sun and Moon can trigger slow earthquakes through resonance, with small stresses comparable to a gentle hand press amplifying fault movements under specific conditions.
A study published in the journal JGR Solid Earth in 2026 suggests that the gravitational tides caused by the Sun and Moon can trigger slow earthquakes by exploiting a resonance effect similar to pushing a swing at the right rhythm. These slow earthquakes
release energy gradually and are imperceptible to humans, but they may precede larger seismic events.
The Resonance Mechanism
The research team modeled tidal stress perturbations using a spring-block system, which simulates the frictional interactions at fault lines. They found that when the period of tidal forces matches a fault’s natural response timescale
—the time it takes to react to stress—small stresses can trigger significant slip events. Although these stresses are very small, typically of the order of a few kilopascals and comparable to the pressure from a gentle hand press, they have been observed to trigger slow earthquakes on some faults,
the researchers noted.
Implications for Earthquake Forecasting
The findings offer a framework for interpreting tidal patterns in slow earthquakes, which could eventually improve forecasting. By analyzing how tidal stress correlates with seismic activity, scientists may infer fault properties from observations of tidal-triggered slow earthquakes,
the researchers concluded. For example, seismologists could reverse-engineer detected earthquakes to determine fault frictional strength and slip thresholds.
However, the model simplifies real-world conditions by focusing on a single fault patch, which may not fully represent complex fault networks. The model is also supposed to replicate a single, isolated fault, which is rarely how faults actually exist,
the team acknowledged. Despite this, the study provides a foundational understanding of how weak, periodic forces can influence seismic behavior.
Historical Correlations and Unanswered Questions
While the study advances understanding, questions remain. Researchers emphasize that tidal stresses are one of many factors influencing earthquakes, and their impact varies by region. The model greatly simplifies reality,
the team noted, as other studies have shown that tidal stresses matter, but exactly how much influence they exert depends on geological conditions specific to the region.