During a serious earthquake:
If you manage to attach your aquarium at several points to your wall, the tank will fail at those points of attachment.
If you manage to attach the entire back wall of the tank to the wall of the house, the entire back wall of the tank will seperate from the rest of the tank.
If you manage to firmly attach the entire tank to the wall, and brace the tank members such that they would not fail, then the entire wall of the house may come down.
Basically, my strategy to deal with the issue would be to get the heck out of the way. Any sized tank can become a projectile in an earthquake. Just have the ability to replace the saltwater and put your corals and fish in plastic bins afterward...not that you would have electricity to run the aerators or powerheads.