Earlier quoted context omitted.
Arizona is actually a good choice. It is geologically stable, doesn't suffer from natural disasters, is somewhat close to Silicon Valley, and has a large enough talent pool to staff TSMC's facilities.
Surely somewhere in the midwest would be more geologically stable and have plenty of access to water. Not sure the proximity to Silicon Valley makes any difference. It's not like factory workers are going to commute from California to Arizona.
Surprisingly, the area is also one of the largest Taiwanese communities in the U.S., which is a bonus for the engineers and their families who will be relocated from the "mothership".
Also, it's actually quite common for high-level Intel staff to fly back and forth from Portland and Phoenix. I am not sure if the same would be said about Taiwan and Arizona, but if they have staff in SV it wouldn't be too far-fetched.