Why does my gas oven shake when I turn it on?

idothe262 questioned:

When I turn on my gas oven, it shakes and the door swings open and shut. Does anyone know why this is? I’ve cooked with a couple uncommon gas ovens before and have never had this problem. My gas oven is ancient (the kind where the pilots are always on). Thankfulness so much, I can’t seem to find the pledge to this somewhere and the thought of baking is starting to scare me!