Actually, Pirates might be kinda fun during an earthquake (so long as it's not too big).
So long as it's not a really big quake (meaning 6.0 and higher), I think the only thing I might worry about are the people who have never felt one before and might panic or something. Everything in DL and DCA is built to withstand and has withstood lots of quakes. Many of the rides would have to shut down for a while anyway so that they could perform safety checks, though. I've never actually felt one while at DL, but then, unless I'm sitting perfectly still, I don't feel most of the smaller ones anyway. If I'm walking I won't be aware of anything smaller than a 4.0 (and I think I've missed a few of those when moving around).