The World's Most Earthquake-Vulnerable Cities

The strongest earthquake to hit Haiti in more than 200 years crushed thousands of structures, from humble shacks to the National Palace and the headquarters of U.N. peace keepers.

Destroyed communications made it impossible to tell the extent of destruction from Tuesday afternoon's 7.0-magnitude tremor or to estimate the number of dead lying among the collapsed buildings in Haiti's capital of about 2 million people.

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International Red Cross spokesman Paul Conneally told the Associated Press that an estimated 3 million people may have been affected by the quake and that it would take a day or two for a clear picture of the damage to emerge. Clouds of dust thrown up by falling buildings choked Port-au-Prince for hours.

And while a massive quake like this one would undoubtedly do damage to any world city, the death toll and degree of destruction has more to do with investment in well-designed infrastructure capable of handling a massive earthquake than the quake itself.

Blame the mortality spread on exponential population growth, increasing poverty and lax or nonexistent building codes. In short: Poor nations--like Haiti--run far greater risk of earthquake fatalities than rich ones.

GeoHazards International, a nonprofit research group aiming to reduce suffering due to natural disasters, measured the lethal potential of seismic disasters facing small and large cities in Asia and the Americas--areas most at risk for seismic calamity. The sample cities spanned both developed and developing countries.

Variables measured: building frailty, potential for landslides and fires, and the rescue, firefighting and lifesaving medical abilities of local authorities.

Kathmandu, Nepal, ranked first in the 2001 study, followed by Istanbul, Turkey; Delhi, India; Quito, Ecuador; Manila, Philippines; and Islambad/Rawalpindi, Pakistan--all of which could expect fatalities in the tens of thousands if disaster struck. The only first-world cities on the list were in Japan: Tokyo, Nagoya and Kobe. Fatalities in these cities were estimated in the hundreds, not thousands. Port-au-Prince was not on the list.

Events since then show the estimates to be fairly accurate, if not low. A 2008 earthquake in China's Sichuan province killed perhaps 15,000 people and left thousands buried under heaps of rubble. The magnitude 7.6 quake that struck the Kashmir region of Pakistan in October 2005 killed more than 73,000 people, many in remote parts of the country, not dense urban centers like Islamabad. Geohazard's study predicted a 6.0 hit on Pakistan's capital would kill 12,500 people.

In a 2004 paper Brian E. Tucker of GeoHazards warned the problem would become worse, citing a study of estimated earthquake fatalities based on population growth and construction changes in northern India.

One scary finding: A magnitude 8.3 earthquake striking Shillong might kill 60 times as many people as were killed during a similar-size quake that hit in 1897, even though the population of the region has increased by only a factor of about eight since then. Reason: The replacement of single-story bamboo homes with multistory, poorly constructed concrete-frame structures, often on steep slopes, has made the population much more vulnerable.

The opposite has happened over the last century in developing nations. Building codes have improved in earthquake-prone regions, as have preparations for disasters. Populations have grown in urban areas, to be sure but at nothing like the rates in Third World cities, where an influx of rural poor has created increasingly dense living arrangements. In the next 20 years the world's population will grow by 2 billion, yet only 50 million will be added to industrialized nations. The gains in the Third World will come mostly in urban centers.

Economic impacts from earthquakes are radically different as well. Tucker finds the cost of the 1994 Northridge, Calif., earthquake was about 1% of the regional gross domestic product, and the cost of the 1989 Loma Prieta earthquake was only about 0.2% of the regional GDP. By contrast, he pegs cost of the 1972 Nicaragua earthquake at 40% of that country's entire GDP, and the cost of the 1986 El Salvador earthquake at 30% of that country's GDP.

For a country like Haiti, the devastation will likely last decades. According to Tucker, Munich Re data indicate that in the period from 1985 to 1999 the world's richest countries' losses to natural disasters averaged about 2% of their GDPs, while the poorest countries' losses averaged about 13% of their GDPs.

--The Associated Press contributed to this story