By golly, I think you're right. I think they were shooting Batman Forever. Warners had absolutely no hesitation about putting the lot back in service. When I got there around 5am on the morning of the quake, they were already surveying the rubble piles. My office up north of the water tower was wiped out by a broken water main, and I was moved off-lot for a couple of weeks, but they got the lot re-opened in days and were well on the way to normalcy a short time later. Pretty amazing recovery.
The funny thing was, there's one stage there that was involved in some epic space adventure, possibly "2001", where the director need much more grid space than the standard stages had. The solution was to disconnect the stage from its foundation, jack it up twenty feet, then build new walls underneath it. That was the stage I always figured would get clobbered in a quake, but amazingly enough it came through pretty well. You can still see the thing poking up above the other stages when you come down the Barham speed trap/hill.
I think the people who build these sets do an amazing job.