Based on historical data of 58 major earthquakes with Mw≥8.0 in offshore subduction zones worldwide, combined with the original physical mechanism of mantle elastic-rigid state transition, this study systematically analyzes the correlation between earthquake occurrence time and tidal phases, and reveals the control law of tidal loading on the triggering of major earthquakes. The results show that the occurrence time of major earthquakes in offshore subduction zones is strictly modulated by tidal phases, presenting a significant magnitude-tidal phase correspondence law: 100% of super-mega earthquakes (Mw≥9.0) occur near the lowest tide/late low tide, 100% of strong-mega earthquakes (Mw8.5~8.9) occur near the highest tide/high water level interval, and 93.8% of strong earthquakes (Mw8.0~8.4) occur in high tide related phases, with only 2 critical low-tide triggered exceptions. This law is highly consistent with the mechanical process of mantle elastic resonance energy dissipation → rigid locking confrontation. The dual modes of super-mega earthquakes triggered by low-tide unloading and moderate-strong mega earthquakes triggered by high-tide loading constitute the core mechanism of tidal triggering of major offshore earthquakes, providing a new theoretical support and data basis for earthquake prediction and solid Earth physics research.
Xiangsheng Yu (Tue,) studied this question.