Consider how much was known about earthquakes, faults, and seismic events in general in 1923 and you can guess they probably had no clue exactly how stupid the decision to build there was at the time. Geologists didn't even understand much about the idea of plate tectonics until after mid-century. As for building a new stadium in another location, there's literally no place to put one anywhere near campus, much less in Berkeley itself. Throw in the environmental issues of ALL kinds (as you mentioned) and that idea is done before the concept even falls out of the first person's mouth.
That stadium is pretty darn old, could they even find the smaller fault lines back then?
I didn't realize the stadium was that old (and I didn't bother looking it up) - I don't make a habit of folloiwng Cal athletics, so I just didn't know.
As far as building a new stadium, look - eventually it's going to have to happen. I guess I don't know what the correct option is as I understand the lack of places to build - I'm originally a Long Islander and they have similar problems out there. But eventually that stadium is going to get to the point where it can't be repaired - what do you do then? With as much debt as the AD is in and nowhere to build and the inability to fix that stadium any furhter, what's next?