Abstract  Major earthquakes in the world, especially the ones above magnitude 7.0 are affected by the positions of celestial objects. The node of the lunar orbit with the earth''s orbit moves westwards on the ecliptic, with a period of 18.6 years. The precession of the lunar ascending node causes the inclinationbetween the moon''s path and the celestial equator to change continuouslyfrom 18.28° to 28.58°. The seismic activities of the mainseismic belts in the world are affected by the period of 18.6 years and onlytheir active periods appear alternately, which shows that different locationsof the moon correspond to different seismic belts or regions on the earth.1425 of the 1861 earthquakes over magnitude 7.0 that happened inthe whole world from 1900 to 1996 occurred at or near the extreme valuepoints of the horizontal component of the tide generating forces, which are77% of the total and much larger than the natural probability, 50%. It isshown that the triggering effect of the celestial objects on an seismic activityis mainly from the horizontal component of the tide generating forces, notfrom the vertical one.