Possible Triggering of Solar Activities to Big Earthquakes (Ms≥8)in the Middle Latitude in China

The relationship between solar activities and big earthquakes (Ms≥8)occurred in middle latitude (20°≤latitudes ≤40°)in China is studied in this paper.It is found that the occurrence dates of most of the big earthquakes are close to the descendent years to minimum years of sunspot numbers, and it implies the correlation between solar activities and earthquakes.It is associated that occurrence of large flood in the middle latitude is negatively correlated with solar activity.The rainfall result in rise of water level.Perhaps the gestated big earthquakes occur easily since the rocks are dipped in groundwater and therefore decreases the shear resistant intensity of rocks.