Given that big things fall over in earthquakes we can't guarantee that they won't be affected! However, having said that, you can use the holes through the tanks to bolt them to a wall, or to tie them to a concrete footing. 

It is important NOT to tie the tanks tightly as the tanks need to expand and contract as they fill and empty with water, so it is very important to leave some flexibility.  Don't use anything that will cut into the plastic of the tank (such as metal strapping).

The tanks are 2.8 ton when full, so take that into account when securing the tanks.