On May 11, 2008, the sun was at 18°N, and as the moon moved north it reached the same latitude. With both celestial bodies at 18°N, their resultant force might have triggered the earthquake.
Quake epicenter and intensity are determined by earth tectonics, but timing might be influenced by other celestial bodies' tidal forces, radiation, and magnetic field. When the three celestial bodies lie in a particular juxtaposition, the resultant combination of their forces could provoke an earthquake.
Two powerful astronomical tides
According to the Guangdong Astronomy Association, the relevant authorities need to pay attention to two powerful astronomical tides in early June.
One will appear at 21:00 on June 3, 2008, a point when the distance between the moon and the earth, at only 357,251 km, is the shortest since Nov 11, 2007. The other will take place at 03:23 on June 4, 2008, when the moon, the sun, and the earth are on the same line. Normally there would be a significant interval between such events. In this case, however, it was no more than 6 hours. Thus a consolidated astronomical tide will be formed, possibly producing a significant impact on atmospheric, oceanic, and solid tides of the earth. After the 8.0 magnitude Wenchuan quake, the tectonic plates were dislocated, and energy release through aftershocks has not fully dissipated the tension.
Clearly, occurrence of such astronomical tides in early June merits vigilance, said the association.
(China.org.cn by Fan Junmei, May 30, 2008)