Hahaha, finally something I know something aboot!!!! Aquamemnon, you have nothing to worry about, if you do, worry about your entire house, not the fish tank!!!
I tank your size would have to be tipped to almost a 40 degree angle from verticle to all over!!! With the prestated 110 lbs/ft2, that would take a pushin force of nearly half a ton!!! Also, in the event of an earth quake, the fish tank is probaby the least likely thing in your house to topple. They actually use huge "fish tanks" to steady skyscrapers. Ok, so they are just water tanks, and there aren't any fish in them, but it's the point that matters.
Water has a natural counterbalancing effect, when you push your tank in one directions the water builds up on the far side, which seems to push the tank further, but then the water slides down in a wave and continues all the water to the other side of the tank, taking 95% of the force with it, thus counterbalancing itself. In an earthquake the movements would be in every direction anyways, so the water would mosty just giggle. If you want to experiment, fill a glass with water that is tall, but not bigger on top than on bottom. Tilt it and let it go and different distances, you'll quickly observe the idea!
Good day all.