Leading Article: Quakes that will shake the world's foundations

YESTERDAY'S earthquake in Los Angeles may not have been the 'Big One'. But the fires, buckled freeways and collapsed buildings gave a foretaste of the disaster that seems bound to hit the United States' second largest metropolis. The City of Angels is in a fatal location, as if willing its own destruction. So, for that matter, is Tokyo, the world's largest agglomeration. Its 31 million inhabitants await a now overdue giant earthquake that will be vastly more devastating than the thousand tremors that shake the city each year.

That these earthquakes will come is certain - the real question is when. The most intriguing long- term issue is their economic, political and social impact. Such disasters can take the spirit out of cities and transform a country's politics. Imperial Portugal was never the same after the earthquake that flattened Lisbon in 1755. The levelling of Managua and the corruption of the aid effort created conditions for the 1979 Sandinista revolution in Nicaragua. Lack of reconstruction after the Sicilian earthquake of 1968 set in train a disenchantment with Italy's traditional politics that is likely to find full expression at the general election on 27 March.

The reverberations from the Big One in Tokyo will be unique because they will be global. The Great Kanto Earthquake that shook Japan in 1923 testifies to the potential shock. It killed 140,000 people and the destruction was equivalent to about 40 per cent of GNP at the time. Should such an event be repeated, economic sages predict a great withdrawal of overseas funds by the Japanese. The world's economy would be sent reeling.

The destruction of an ultra-modern city such as Tokyo or Los Angeles may prompt a rethink of urban life in the 21st century. If sophisticated buildings fail to survive the forces of nature, those disenchanted with high-rise cities will have a powerful argument on their side.

Devastation will raise the question of why humans set themselves so suicidally against nature's dictates. On 9 January 1857, a large earthquake gave the village of Los Angeles an indication that it was poorly founded. Tokyo has been reminded of its faults roughly every 70 years. Yet still these cities have grown. Perhaps the human lifespan is simply too short and the Big One too infrequent to persuade people to live wisely rather than dangerously.