The Bam temblor, which registered at least 6.3 on the Richter scale, killed some 30,000 of the town's 100,000 population, according to latest projections. Some experts estimate that a quake measuring 6.0 on the scale could leave as many as a million of Tehran's 12 million inhabitants dead.

That explains why the city's mayor, Mahmoud Ahmadi-Nejad, has launched the slogan: "Pray there is no earthquake in Tehran."

Maziar Hosseini, the town hall crisis centre manager, explained: "Tehran and the surrounding region is situated over four major fault lines, running from east to west in the north, the two Ray faults to the south and the north-south fault which cuts from the eastern suburbs of Tehran to the Caspian Sea."

In the face of the fears of the population, the authorities are reluctant to discuss which areas might be most at risk.

But with the exception of the northern fault, which runs under the wealthier and less-populated areas of Tehran, the faults all run beneath densely populated poorer quarters, packed with rundown old houses, the bustling city market and even out to the satellite town of Shahr-e Ray.

"About 40 percent of all Tehran's housing is in a dilapidated state. The buildings have no metal structure and do not conform to any anti-earthquake regulations. They should all be razed to the ground and rebuilt," Hosseini said.

"It would require two billion dollars to modernise all the old rundown houses in the capital."

As well as the 40 percent of old housing, many new buildings have been put up without any regard to the threat of an earthquake. In many cases, buildings of more than 10 storeys have been erected directly over the faults.

"We have a 10-year plan, worked out with the help of Japanese specialists, which aims to reduce the number of old rundown buildings and those which do not comply with earthquake regulations to about 10 percent of the total," he added.

Ahmadi-Nejad also announced a plan to be put into action in case of emergency.

"We need to reinforce the hospitals, the fire stations, bridges, reservoirs, bakeries and electric pylons in order to deal with an emergency situation," he said.

In a city which is a motorist's nightmare and becomes worse by the day, the authorities also want to build a network of roads for use by the emergency services.

The Bam earthquake has reawakened the fears of the population.

"You really need a house in the country well outside the city to take refuge in in case of an earthquake," said Leyla, a housewife in her 50s.

A town hall official, speaking on condition of anonymity, said: "With the four fault lines and many smaller onces, we believe that in case of a powerful earthquake nowhere is entirely safe and even the town of Karaj, with a population of more than one million, more than 40 kilometres (25 miles) to the west of Tehran, could be hit."

But at least Mohammad Mokhtari, head of the capital's seismology faculty, has some words of comfort when he says: "For the time being, the different fault lines in the region have remained very quiet."

TERRA.WIRE