Statistical Test for the Modulation of Global Deep Focus Major Earthquakes by Annual Tidal Stress

This study examines the potential modulation of annual tidal stress on the timing of global deep focus major earthquakes (magnitude Mw ≥ 7.0, depth ≥ 300 km). Based on 61 qualifying events from 1973 to 2024, the tidal phase angle within the annual cycle was computed for each earthquake. Analysis using Rayleigh’s test for uniformity yields a p value of 0.244, which exceeds the 0.05 significance threshold. This indicates that the occurrence times of deep focus major earthquakes are statistically uniformly distributed over the annual cycle, and no significant modulation by annual tidal stress is detected. The result provides a new observational constraint for understanding the triggering mechanisms of deep focus earthquakes.