Until this week, New Orleans had been unnaturally lucky with hurricanes since the monstrous Camille roared through in 1969. Maybe the immunity was a voodoo thing, or thang, to use the local term of art. But amulets, fetishes and dolls don't work forever. The city sits a bayou away from the Gulf of Mexico, which is basically a giant nursery for hurricanes. The law of averages guarantees that most will miss the Big Easy, but also that a few won't.

Katrina, one of the few, was at least polite enough to have its deadly eye just graze the lovely city on the east, meaning that maximum winds there were "only" 120 miles an hour. Gulfport and Biloxi, in Mississippi, seem to have had the worst of it -- not that I would try to tell that to the 10,000 people who huddled in the New Orleans Superdome while chunks of the roof blew away, or the others who didn't make it to safety and whose fate is not yet known.

None of this was a surprise -- New Orleans is below sea level, wedged between Lake Pontchartrain, the Mississippi River and the Gulf, and is kept dry by a system of levees, dikes, canals and massive pumps. Everyone knew these defenses could handle an average hurricane but not a really big one such as Katrina. Yet a million people living in the New Orleans area, not to mention the rest of us, managed to put that inconvenient fact out of their minds.

It's paradoxical, when you think about it, that we have such a sense of urgency about preventing acts of terrorism that we will spend any amount of money to reduce the risk. But we are so laid-back about natural disasters -- which are absolutely inevitable, take more lives and can have devastating economic impact -- that we buy protection only grudgingly. There are plenty of plans on the books for new floodgates, levees and pumps in New Orleans, but funding comes in at a trickle.

It's not just Americans who have this bias: Imagine how many people might have been saved last December if a few million dollars had been spent on an early warning system for Indian Ocean tsunamis. Then again, tsunamis are so rare that they almost never come up on anyone's list of things to worry about. Hurricanes, by contrast, are common, reliable and deadly -- and it's long been known that New Orleans, because of the minus sign in front of its elevation, was a soft and vulnerable target.

"I remember, oh, it must have been 30 years ago when I was in school, and a professor said that the worst-case scenario would be a hurricane passing right over New Orleans," said Maxx Dilley, a policy adviser with the U.N. Development Program in Geneva. Dilley, formerly at Columbia University, has spent years studying the risks of natural disasters and analyzing ways of lessening their impact.

Of course, we have other catastrophes to worry about if we choose to. Los Angeles and San Francisco sit beside the San Andreas Fault, which someday will try its best to reduce those great cities to rubble. Mount Rainier, the gorgeous volcano overlooking Seattle, could imitate its neighbor Mount St. Helens and blow its top. And then there are the quotidian small-scale disasters: tornadoes, wildfires, flash floods, mudslides.

Dilley recommends that we build our settlements with these hazards in mind, and he cites earthquake-prone Japan as a model. Japan has strict building codes, educates citizens on preparedness and does cutting-edge research in earthquake science. But despite all that foresight, Japan suffered huge losses in the devastating Kobe quake of 1995. "There's no way you can reduce these risks to zero other than staying away from these [risky] places entirely," he said.

I confess to having little sympathy for those who build multimillion-dollar homes in the steep canyons around Los Angeles knowing full well that when there's a drought (and there will be a drought) the houses may well burn to the ground, and that when there's too much rain (and there will be too much rain) they may well slide away. And I worry that all the coastal development on barrier islands, like the Outer Banks, just means bigger losses when the next hurricane comes through (and it will come through).

But New Orleans doesn't have a choice -- it is where it is. Unless we plan to move the city to higher ground, we'd better find the money for bigger levees and bigger pumps.