I think you are right as there are ways to mitigate natural disasters. The question is whether or not there is political will to pay for the mitigation measures until the disaster happens. Winnipeg had been flooded severely several times in the last hundred years until the 1970s when a giant floodway was created which could divert a river's worth of water around the city. Since then the floodway has saved the city from numerous large floods and has just recently been expanded to provide protection for a 1 in 700 year flood.

It seems unfortunate the city was catastrophically flooded several times before that monetary expenditure was politically acceptable.