Correlation between giant earthquakes and lunar phases in seven Indo-Pacific subduction zones and Mongolia.

To clarify the relationship between lunar phases and the occurrence of giant earthquakes, the lunar phases of earthquakes worldwide with magnitudes (MW) ≥ 8 from 1900 to 2024 were analyzed. The null hypothesis – that these major earthquakes occur randomly – was tested and statistically rejected for Southern Chile, Peru, the Japan Trench, the Kuril Islands, Samoa and Tonga, and Mongolia. This rejection indicates that the occurrences of these earthquakes are not random. Specific lunar phase ranges, referred to as Dangerous Lunar Phases (DLPs), where major earthquakes are more likely to occur, were identified for each subduction zone and Mongolia, using the delay angle from the spring tides. DLPs in Southern Chile and Peru tend to align with spring tides, whereas those in the Japan Trench, Kuril Islands, Samoa and Tonga, and Mongolia align more closely with neap tides. The analysis of Peruvian earthquakes suggested that MW = 7.5 was the optimal lower threshold. A method was proposed to predict DLPs for future giant earthquakes at significance levels of 0.01 and 0.05, and it was applied to the Japan Trench before the Tohoku 2011 event. Both the foreshocks and the mainshock of Tohoku 2011 occurred within the DLP. Research highlights: We analyzed the lunar phases of all global earthquakes with MW ≥ 8 that occurred between 1900 and 2024. We found that giant earthquakes in several subduction zones and in Mongolia show statistically significant dangerous lunar phase ranges (DLP). We proposed a method to evaluate the DLP for the next giant earthquake. Applying this method to events before the 2011 Tohoku earthquake showed that both the foreshocks and the mainshock occurred within the calculated DLP. Heightened vigilance during DLP periods may help reduce the damage caused by giant earthquakes. [ABSTRACT FROM AUTHOR]