It isn't just an urban myth: life in a city really is getting more dangerous, and the sources of peril are not just human ones like muggers and reckless motorists. A report by UN-Habitat, an agency responsible for human settlements, says the number of natural disasters affecting urban populations has risen four-fold since 1975.
Some of the reasons are obvious, others less so. As the world's population grows, people are crowding into mega-metropolises, where life's risks are horribly concentrated. The after-effects of a natural disaster can be especially dire in a vast, densely-packed area where sewers fail and disease spreads.
At a pace that no urban planner can control, slums spring up in disaster-prone areas—such as steep slopes, which are prone to floods, mudslides or particularly severe damage in an earthquake. Many of the world's cities are located on coasts or rivers where the effects of climate change and extreme weather events, from cyclones to heatwaves to droughts, are brutally and increasingly felt. Economic dislocation and human pain are also caused by events (like recent floods in the Indian city of Kolkata, see above) that are too small to grab global headlines.
But there is no reason for the sort of fatalism that regards disasters, and their disproportionate effects on the urban poor, as something that has "always been with us" and will inexorably get worse.
Intelligent planning and regulation make a huge difference to the number of people who die when disaster strikes, says Anna Tibaijuka, UN-Habita's executive director. In 1995 an earthquake in the Japanese city of Kobe killed 6,400 people; in 1999 a quake of similar magnitude in Turkey claimed over 17,000 lives. Corrupt local bureaucracies and slapdash building pushed up the Turkish toll.
The Indian Ocean tsunami of 2004, which killed at least 230,000 people, would have been a tragedy whatever the level of preparedness; but even when disaster strikes on a titanic scale, there are many factors within human control—a knowledgeable population, a good early-warning system and settlements built with disasters in mind—that can help to minimize the number of casualties.
In some places, says Saroj Jha, a disaster specialist at the World Bank, tragic events have been a spur to serious national efforts to learn lessons and make buildings and infrastructure more robust. Often this has benefits that go far beyond the disaster-stricken area. He cites Turkey, India, Vietnam, Sri Lanka and Indonesia as countries that have learned from catastrophes. For example, after a quake in Gujarat which killed 20,000, India trained a small army of engineers, architects and builders to raise the quality of construction.
The World Bank has recently started to focus more on avoiding disasters, rather than just helping to respond to them. There is more awareness that disaster-prone projects—such as clams which could burst—are worse than a waste of money.
Given that events like earthquakes and tsunamis cannot be escaped, the bank is also doing more to help poor countries prepare for the worst. There are economic reasons for this, as well as humanitarian ones. Many vulnerable cities are big contributors to the surrounding country's GDP—so an urban disaster could wreck an entire national economy. These include Tehran (which produces 40% of national GDP), Dhaka (60%), Mexico City (40%), Seoul (SOX) and Cairo (50%).
And some of these urban spaces are disasters waiting to occur. The Bangladeshi capital of Dhaka (with a population of 11. 6m and rising) is built on alluvial terraces, exposed to flooding, earthquakes and rising seas. Tehran is in such an earthquake-prone area that some have suggested moving the entire city of 12m people. That will hardly happen; but better foundations could save countless lives if—or when—an earthquake strikes.