Hi all - This was posted on another forum I'm on - I am pretty sure Roger has info on this - do you have something roger?
,i>I'm pure speculating again, but it seems that the cyclical gravitational tugs of the moon and the sun on Earth could have EQ influence (mostly gravitational) in these many ways:
1-Lunar daily (Earth rotation)
2-Lunar monthly (Lunar orbit)
3-Lunar apogee/perigee (Lunar distance)
4-Solar daily (Earth rotation)
5-Earth apogee/perigee (Earth orbit-Sun distance)

I do not believe that the planets have enough gravitation and/or other particle interaction with Earth to come close to the Earth-Moon-Sun interaction. Their distance, mass and geomagnetic particle influences are far less.

It seems reasonable to me that if there is cyclical celestial triggering of EQs that the above influences, primarily gravitational, would be the strongest.

However, I've done no calculations nor seen any research to validate or refute my speculation. ;) :)

Canie