You can't prevent a hurricane or an earthquake but you can certainly mitigate the damage it would cause.

IMO part of the reason New Orleans was so badly hurt by Katrina was the lack of a "defense in depth". Everything depended on the levees holding; once the levees failed, the rest of the city had no protection. It was the classic example of a Gary Larson "Far Side" igloo (hard and crunchy on the outside, soft and chewy on the inside).