updated 10:41 a.m. ET, Sat., April. 5, 2008

Quick: Name the Western U.S. city most vulnerable to a terrorist attack. Is it Los Angeles, with its crowded roads that make quick escape impossible? San Francisco and its iconic bridge? Or Seattle with its Space Needle and busy port?

Try Boise, Idaho, with its, um, potatoes.

A new study funded largely by the Department of Homeland Security ranked 132 American cities according to vulnerability to terrorist attacks. Boise was the only city in the western half of the country to make the top 10.

"To be honest, we're a little bit surprised," said Adam Park, a spokesman for Boise, a landlocked city of 200,000 where the big event this weekend is a Professional Bull Riders invitational.

The rest of the top 10 -- led by New Orleans and including New York and Washington, D.C. -- were largely East Coast cities. Los Angeles was No. 41, followed by San Francisco at 66 and Seattle at 87.

"Is this a typo or what?" asked Bobbie Patterson, executive director of the Boise Convention and Visitors Bureau. "Where in the world did this information come from?"

It came from four years of work and a series of mathematical formulas developed by Walter W. Piegorsch, a professor at the University of Arizona, with help from Susan Cutter at the University of South Carolina and Frank Hardisty at Pennsylvania State University. The study was published in December by Risk Analysis, a well-regarded journal.

The researchers assessed the vulnerability of each city to a terrorist attack based on three things: socioeconomics, infrastructure, and geophysical hazards such as the potential for flooding or fire.

The analysis measured not whether a city would make an attractive target to a terrorist but rather how well it could withstand an attack, Piegorsch said.

"This wasn't a question of what places a terrorist wants," Piegorsch said. "The targetability is not an issue here; it's the vulnerability if they were targeted."

The researchers color-coded that vulnerability, assigning green to areas with low vulnerability to a terrorist incident and resulting casualties, yellow to those with high vulnerability but low casualties, and red to those with high marks in both vulnerability and casualties.

A deficiency in one category could overshadow high marks in another. A city with well-built bridges might find itself higher on the list if its high-density population makes evacuations difficult.

This explains Boise's red reading. Despite good marks for socioeconomics and infrastructure, Boise has a "high geophysical risk factor," Piegorsch said. The property damage caused in the 1990s by wildfires and floods in the area help create that score, Piegorsch said, because it showed what can happen in the future should terrorists prey on the area's weaknesses. The city is just west of the Lucky Peak Reservoir, which holds nearly 10 billion gallons of water.

"If a terrorist were to harm the city, in a place like Boise they could try to do some flood damage," he said. "If the city is very vulnerable to wildfires, then one match is lit and you're all set."

San Francisco and Los Angeles got low ratings despite their frequent wildfires and earthquakes because they've grown adept at handling disasters, Piegorsch said.

"They know how to deal with it," he said. "They've got modern buildings. They've got really well-coordinated emergency response teams. They've got it all together."

San Francisco Mayor Gavin Newsom said he wasn't feeling as confident. "I'm not sleeping much better today being 66 out of 132 urban areas," he said, adding that he is concerned some cities might lose federal funds for preparedness based on such studies. "I don't think the twin towers would have come up in this quadrant."

"I'd like to say, 'Oh, it's great because we're remarkably so well prepared, but I don't think we are to the degree we need to be, and I don't think -- and I'm sure the authors would agree -- we should reduce our efforts or inhibit our disaster response program," he said.

Amy Kudwa, spokeswoman for the Department of Homeland Security, said the study will not be used to determine grants and is just one of many research projects.

"We don't have a monopoly on good ideas and so we facilitate research," said Kudwa, adding that she could not say how much DHS paid for the research. DHS gives approximately $4 million a year to a research center based at the University of South Carolina that, in turn, sponsored Piegorsch's project. Piegorsch said the study also received about $400,000 each from the Environmental Protection Agency and the National Cancer Institute.

Henry Willis, a Rand Corp. risk analysis expert, called the study a "novel" look at vulnerability but said he had questions about its findings. "In this new measure of vulnerability, do they have the right set of factors? That's the unanswered research question," Willis said.

And just because Boise is vulnerable doesn't mean it faces greater risk than Los Angeles, San Francisco or other cities, Willis said. "Vulnerability is only one factor of risk, and risk is only one factor when considering how to allocate resources," he said.

At the Fancy Pants boutique in downtown Boise, sales associate Katie Bohannon said she wasn't feeling particularly vulnerable. "I'm less scared than I am confused," she said. "I don't really see why Boise would be on the top of that list."

Staff researcher Magda Jean-Louis contributed to this report.

URL: http://www.msnbc.msn.com/id/23964321/

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