Generally speaking, human beings can do whatever he wants and discover as many technologies as possible it will still remains impossible to do anything against Nature. Actually, since humanity exists we have learnt to live and survive with the worst surprises Nature has offered us.

In this extent if we think about urbaniziation it very important for cities' organisation to do their best to prevent any hazards. The most important thing is to be able to measure the risk. We can define risk as the multiplication of the hazard by the vulerablity. For instance an enormous storm in the middle of the Sahara does not present any risks...

In other words it is essential to be able to wheight the importance of risks in urban areas since it is impossible to be "over protected" of every risks for obvious financal reasons. Cities have to make difficult choices to protect its population against particular hazards.

For a better understanding, let's take as an example my hometown. I live in Rennes in western part of France : Bretagne. This 200 000 inhabitants cities is used to be the capital of Bretagne and its city center is build of old buildings (lot of building were built in the XV, the XVIII and the XIX centyry). An other thing that worst to be said is that both rivers Ille and Vilaine pass through Rennes' downtown. For this reason if I had to choose the most threatening hazard in Rennes I would say obviously flood. Actually, banks of the rivers make up the city center. 

Fire in Rennes city center on the 21th of june 2010

Furthermore, even if it is not a natural hazard I think that arsons and fire can be part of this disscussion. Actually, arson had caused several death in the last few years. That is why I would choose fire as the second priority for protecing Rennes's population. Actually, because of most of buildings in Rennes are very old and made of wood, fire can spread very fast and emergencies exit are often missing is those buildings.

To conclude, I would say that Rennes is not exposed to many natural hazards but Renne city has really to take care of the two main hazards I mentionned.