"It's not just because the building codes don't mandate taking quakes into account, but also because of the underlying bedrock. It is extremely hard and a major quake would cause it to shatter. So the damage would be extensive and massive. ..."
Waitasec...
That is exactly the opposite of nearly everything I've ever read about earthquakes...
The worst damage occurs when buildings have been build on sandy soil and/or landfill, ESPECIALLY where the water table is high.
Solid ground, like the highlands in the San Francisco area that weren't as badly shaken in the 1906 quake, usually sustains LESS damage. It's the LIQUIFACTION that causes major damage - LIQUIFACTION basically causes sandy/landfill areas with high water tables to act somewhat like QUICKSAND...
Now, if you're talking about a "locked" fault, that "unzips" along a great length, yes, that is a major factor in the force and amount of damage in a quake, but the type of underlying bedrock isn't quite as much of a factor in that.
One can have a violent "unzipping" of a fault, whether it's in sandstone or granite...
Then of course, it also depends on the depth of the epicenter, and other factors...