The floods in southern Alberta are the worst since records were kept.
People live where it is convenient- both have been centers for over 100 years. Both have large business cores with business and residential high rises.

Cities as large as Calgary (1.2 million metro) or Edmonton (1.1 metro) are not movable.

California and other west coast cities are subject to earthquakes. Florida to Texas suffers from hurricanes, the Midwest has tornados (as well as floods).

Should everyone move to the snowy (but arid) and stable Canadian Shield? Only a few trappers and miners can make a living there.

This "shouldn't have done it" talk is nonsense.