My rack isn't secured to the wall, but if it fell over in an earthquake my whole house would be gone. I have a couple aquariums, and they are secured to the walls.

I do have an evacuation plan too. I've actually been evacuated before due to wild fire. I didn't have all the critters I have now, but on my own I loaded up three cats, a dog, and a few dozen rats, their food, and a few personal possessions and left in less than a half hour. It'll will take longer than that now, but I have quite a few more critters, but also hubby is around now (he was deployed when I was evacuated) which will help. I want to go through the motions just to practice, but we haven't gotten to do that yet.