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close this bookNatural Disasters - Be Prepared! (UNESCO, 1997, 50 p.)
View the document(introduction...)
View the documentMonth by month
View the documentSafety first
View the documentA decade for international action
View the documentNature on the rampage
View the documentMaking cities safer
View the documentThe do’s and don’ts of risk reduction
View the documentSounding the alarm
View the documentWomen in the front line
View the documentInsurance: halting an ominous trend
View the documentFact file
View the documentCommentary Federico Mayor
View the documentGREENWATCH New Caledonia: threats to biodiversity
View the documentHeritage. Taxila - The cradle of Gandhara art
View the documentREFLECTIONS. Spreading the world
View the documentInterview. Manuel Elkin Patarroyo
View the documentAUTHORS

Making cities safer

The defences of overcrowded cities with fragile buildings and vulnerable infrastructures must be strengthened


The aftermath of the Kobe (Japan) earthquake of 18 January 1995 [© Haruyoshi Yamaguchi/Sygma, Paris]

All over the world, economic expansion, use of new technologies and growing - interdependence are boosting the risk of natural disasters. Cities need to draft master-plans to cope with them - assessing threat, predicting its effects and proposing action.

Earthquakes, which cause most natural disasters, can set off chaos in the crowded slums of poor countries and topple badly-constructed, badly-located buildings. In rich countries, ageing populations and a growing reliance on technology are weakening the defences of towns and cities. There is also more of value to be destroyed.

Landslides are another big cause of urban disasters, often related to earthquakes, when housing is built on steep or unstable hillsides. Volcanoes are more predictable than earthquakes, but because they lie dormant for hundreds of years, the danger from them is often ignored and people build and live on their slopes. Severe flooding threatens towns and cities which are set among denuded mountains where there are frequent thunderstorms.

Natural disasters can wreck social structures, production, employment and income, as well as cause physical damage. Building regulations are crucial. In the 1995 Kobe earthquake in Japan, countless buildings were destroyed because of inadequate rules. Where they exist in developing countries, such regulations are seldom enforced. In the Erzincan (Turkey) quake of 1992, half the medium-sized reinforced-concrete buildings were destroyed. This is four times more damage than at Kobe and twelve times more than at Northridge (California) in 1994. Even where modern buildings are only slightly damaged, their movable contents - in the case of laboratories, hospitals, offices, museums and art galleries - can be destroyed.

A rescue team extracts a survivor from the ruins of a Mexico City building after the 1985 earthquake. [© T. Campion/Sygma, Paris]

Roads and bridges are vital in an emergency. But earthquakes move and damage them. At Northridge, ten viaducts and 157 overpasses were heavily damaged, costing some $1.5 billion. At Kobe, the loss was from four to five times greater and the urban transport system was damaged in 1,257 places. Rescue and recovery from a major earthquake in Istanbul would depend heavily on vulnerable roads and bridges linking the city to Europe.

Underground pipelines can also break, leaking water and gas and setting off fires. This hampered rescue work at Kobe, where more than 150 fires could not be put out because the water supply to fight them failed, as did the damaged road network.

In human terms, single-parent families, women, handicapped people, children and the elderly are the first victims of a natural disaster. Indirect economic damage from an earthquake includes loss of production and tax revenue and increased unemployment payouts.

Northridge was the most costly earthquake in U.S. history. At $200 billion, Kobe was the most expensive urban disaster of modern times. In both, the damage worked out at between $40,000 and $50,000 per affected person. At Erzincan, it was only about $10,000 because of the very limited infrastructure and industry.

Such huge losses will occur again. A big quake in Istanbul would probably cost about $50 billion - about a fifth of Turkey’s 1996 Gross National Product (GNP). A repeat of the 1923 Kanto earthquake in the Tokyo region would cost perhaps sixteen times more than Kobe, or two-thirds of Japan’s 1994 Gross Domestic Product (GDP). Another San Francisco quake as big as the tremor of 1906 (8.3 on the Richter scale) would cause losses seven times greater than at Northridge.

Vehicles were crushed when an apartment building collapsed onto its parking lot during the Northridge (California, U.S.A.) earthquake in January 1994. [Blake Sell/Reuters/MAXPPP, Paris]

An old house in a Turkish village which collapsed after being weakened by several earthquakes. [© Mark Edwards/Still Pictures, London]