Astronomic background of global huge earthquakes at beginning of 21st century

Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.

Correlation between lunar node tide and great earthquakes

This study selects six consecutive 18.6 years of global M≥7.0 earthquakes,calculates the lunar declination angle based on the time of the earthquakes,and divides the global earthquakes into 13 research regions according to the global plate distribution facts to explore the lunar infl uence of earthquakes.The relationship between the lunar declination angle and these earthquakes is analyzed.The analysis results show that when the moon advances to a certain interval of its declination angle,the earthquakes are concentrated in a certain research region,whereas other research regions are relatively calm,providing a scientifi c basis for medium and long-term earthquake predictions in each research region.The 18.6-year cycle is the lunar declination angle change cycle,and it is also the major nutation cycle of the earth’s motion and lunar node movement cycle.This is,in reality,the eff ect of the lunar node tide,which is worthy of further study.