When Qx lived there, he wasn't concerned about a quake unless it got up above 6. Thankfully, that didn't happen near him. Trouble is, Taipei is built a lot on a flood plain. And liquifaction has to be a concern. Supposedly the problem is mitigated by many deep concrete piles being build deep into the ground under any significant building. Not sure how effective that will be during a big one, however.
Evidently Taipei 101 also has a huge heavy ball at the top acting as an active damper on quake forces shaking the building back and forth.