August 30, 2005
Tuesday

As rescue teams searched the devastation along the Gulf Coast on Tuesday, it appeared likely that Hurricane Katrina claimed the majority of its victims with its storm surge - something that hasn't happened with a mainland U.S. hurricane in nearly half a century.

Although the precise toll won't be known for days, early, unofficial reports from Mississippi and New Orleans indicated that dozens of people - and perhaps more than 100 trapped in places that were under evacuation orders - were killed by water pushed into the shore by the force of the hurricane's winds.

The last time a hurricane so swamped the coastline was in virtually the same spot, when Camille came ashore at Pass Christian, Miss., in August 1969, with winds estimated at 190 mph, and a storm surge measured in excess of 22-1/2 feet. The water killed 143 people in Mississippi and Alabama. But most of Camille's victims were claimed when the storm's remnants killed another 150 people in Virginia after dumping nearly 30 inches of rain over the Blue Ridge Mountains.

While the immediate comparison has been between Camille and Katrina, hurricane experts say Monday's storm had a much bigger reach than the tightly wound Camille. Katrina's winds were up to 140 mph and extended 100 miles from the storm's center.

To a slightly older generation, the situation recalled Hurricane Audrey, which sent storm surge up to 25 miles inland along the southwestern coast of Louisiana and killed nearly 400 people in 1957.

In the years since Camille, hurricane researchers have noted that only about 6 percent of deaths from the storms striking the United States have been the result of storm surge, with inland flooding, winds and tornadoes spun from storms taking the greater toll.

"We've been lucky to hold down the toll from storm surge in recent decades, but we've always stressed that the greatest threat to human life in hurricanes, historically, is from surge," said Edward Rappaport, deputy director of the National Hurricane Center in Miami.

"One of the most vulnerable to calamity has been New Orleans and the surrounding low-lying area," he said.

Rappaport said that even though Katrina spared New Orleans its worst winds by passing slightly east, the backspin of the storm still helped generate waves from Lake Pontchartrain that overtopped and weakened levees protecting the city, although in phases that have allowed many trapped residents to reach safety.

Farther east, around Gulfport and Biloxi in Mississippi, the surge exceeded Camille's reach, with reports of water flooding structures up to 30 feet above sea level.

Officials said the surge may have caught people off guard because they knew the storm wasn't as strong as Camille, but Rappaport said forecasters have learned that "the size of a storm out over the ocean matters almost as much as the strength of the winds when it bumps into land."

Although Katrina had weakened to a Category 3 storm by the time it made Monday's second landfall, in Mississippi, the reach of the storm was so great, that didn't matter.

And the surge in the Back Bay of Biloxi was probably worsened by the runoff from up to a foot of rain that accompanied the hurricane, Rappaport said.

Officials along the Gulf noted that a combination of recent near-misses for the area, the benchmark of Camille and the sheer difficulty of joining the evacuation might have deterred some people from leaving.

Although as many as 80 percent of New Orleans' 480,000 residents did flee, "there's a certain element of the culture in the city that says you don't leave for hurricanes," said John Beggs of Louisiana State University's Hurricane Center in Baton Rouge. He's an associate professor of sociology who researches the social networks and interactions of people trying to cope with hurricanes.

Co-researcher Jeanne Hurlbert said that while some people chose to stay in New Orleans, "a lot of people who were left behind were too old, too sick or too poor to go, and that's a big factor in the very ugly situation that we're facing in the aftermath."

Beggs said people who are poor, with few resources, are often more reluctant than those who are better off to leave their homes behind, even if they can. "And even if you're middle-class, it can be daunting to have to pack up the car and find someplace to stay inland, particularly if you have to do it several times a season.

"Really, it's impressive that as many people got out between Friday and Sunday as did go. The authorities made it sound big and scary enough that most who could go did respond, but apparently not everyone."

On the Net:

http://www.nhc.noaa.gov

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