[Little Pig]

Tsunamis wouldn’t have any impact at all on a floating city, unless it was so close to shore that it ended up run aground during a tsunami’s initial retreat from the shore. Tsunamis at sea are rarely more than a couple of feet high, and their peak-to-trough is so long you wouldn’t notice them at all.

Now, rogue waves on the other hand would be a serious hazard. However, the benefit to a floating city is that it can be moved to avoid all but the largest areas of heavy seas.

[Vaquero]

True. Folks vacationing in Phuket etc in 2004 who were offshore barely felt the tsunami.

[JimRed]

However, the benefit to a floating city is that it can be moved to avoid all but the largest areas of heavy seas.

Or even seasonal relocation. North for the summer, south for the winter.