I personally don't have very tall racks. And the racks I do have, are pretty well balanced/lower center of gravity where it wouldn't fall any ways during a large quake.
But if you really wanted to, it wouldn't hurt to tether them to a wall bracket like furniture. Or at least maybe instal a pin lock(like RBI's racks) where the tubs won't slide out without moving the pin. This will keep snakes in their respected enclosures.
We haven't had a large quake in 24 years. Everything else in between have been pretty tiny and insignificant.
I don't live in a high fire zone, but it's always nice to have an evac plan regardless.
In my emergency kit, I have:
- shipping heat packs
- roll of flexwatt
- spare thermostat
- pillowcases and small totes for snakes (pillowcases for the big stuff and totes for the smaller guys to prevent them from getting smashed)
- insulated cooler (which is the emergency kit itself) to keep snakes in a stable temperature in a pinch.
- old rags
- paper towel
- water bottles